diff --git a/src/CBot/CBotClass.cpp b/src/CBot/CBotClass.cpp
index f1a658ad..628bb907 100644
--- a/src/CBot/CBotClass.cpp
+++ b/src/CBot/CBotClass.cpp
@@ -36,7 +36,6 @@
 #include "CBot/CBotCStack.h"
 #include "CBot/CBotDefParam.h"
 #include "CBot/CBotUtils.h"
-#include "CBot/CBotFileUtils.h"
 
 #include <algorithm>
 
@@ -364,69 +363,70 @@ void CBotClass::RestoreMethode(long& nIdent,
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotClass::SaveStaticState(FILE* pf)
+bool CBotClass::SaveStaticState(std::ostream &ostr)
 {
-    if (!WriteWord( pf, CBOTVERSION*2)) return false;
+    if (!WriteLong(ostr, CBOTVERSION*2)) return false;
 
     // saves the state of static variables in classes
     for (CBotClass* p : m_publicClasses)
     {
-        if (!WriteWord( pf, 1 )) return false;
+        if (!WriteWord(ostr, 1)) return false;
         // save the name of the class
-        if (!WriteString( pf, p->GetName() )) return false;
+        if (!WriteString(ostr, p->GetName())) return false;
 
         CBotVar*    pv = p->GetVar();
         while( pv != nullptr )
         {
             if ( pv->IsStatic() )
             {
-                if (!WriteWord( pf, 1 )) return false;
-                if (!WriteString( pf, pv->GetName() )) return false;
+                if (!WriteWord(ostr, 1)) return false;
+                if (!WriteString(ostr, pv->GetName())) return false;
 
-                if ( !pv->Save0State(pf) ) return false;             // common header
-                if ( !pv->Save1State(pf) ) return false;                // saves as the child class
-                if ( !WriteWord( pf, 0 ) ) return false;
+                if (!pv->Save0State(ostr)) return false;             // common header
+                if (!pv->Save1State(ostr)) return false;                // saves as the child class
+                if (!WriteWord(ostr, 0)) return false;
             }
             pv = pv->GetNext();
         }
 
-        if (!WriteWord( pf, 0 )) return false;
+        if (!WriteWord(ostr, 0)) return false;
     }
 
-    if (!WriteWord( pf, 0 )) return false;
+    if (!WriteWord(ostr, 0)) return false;
     return true;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotClass::RestoreStaticState(FILE* pf)
+bool CBotClass::RestoreStaticState(std::istream &istr)
 {
     std::string      ClassName, VarName;
     CBotClass*      pClass;
     unsigned short  w;
 
-    if (!ReadWord( pf, w )) return false;
-    if ( w != CBOTVERSION*2 ) return false;
+    long version;
+    if (!ReadLong(istr, version)) return false;
+    if (version != CBOTVERSION*2) return false;
 
     while (true)
     {
-        if (!ReadWord( pf, w )) return false;
+        if (!ReadWord(istr, w)) return false;
         if ( w == 0 ) return true;
 
-        if (!ReadString( pf, ClassName )) return false;
+        if (!ReadString(istr, ClassName)) return false;
         pClass = Find(ClassName);
 
         while (true)
         {
-            if (!ReadWord( pf, w )) return false;
+            if (!ReadWord(istr, w)) return false;
             if ( w == 0 ) break;
 
             CBotVar*    pVar = nullptr;
             CBotVar*    pv = nullptr;
 
-            if (!ReadString( pf, VarName )) return false;
+            if (!ReadString(istr, VarName)) return false;
             if ( pClass != nullptr ) pVar = pClass->GetItem(VarName);
 
-            if (!CBotVar::RestoreState(pf, pv)) return false;   // the temp variable
+            if (!CBotVar::RestoreState(istr, pv)) return false; // the temp variable
 
             if ( pVar != nullptr ) pVar->Copy(pv);
             delete pv;
diff --git a/src/CBot/CBotClass.h b/src/CBot/CBotClass.h
index 0f9a8ce4..eeafe2d1 100644
--- a/src/CBot/CBotClass.h
+++ b/src/CBot/CBotClass.h
@@ -331,18 +331,18 @@ public:
     static void ClearPublic();
 
     /*!
-     * \brief SaveStaticState
-     * \param pf
-     * \return
+     * \brief Save all static variables from each public class
+     * \param ostr Output stream
+     * \return true on success
      */
-    static bool SaveStaticState(FILE* pf);
+    static bool SaveStaticState(std::ostream &ostr);
 
     /*!
-     * \brief RestoreStaticState
-     * \param pf
-     * \return
+     * \brief Restore all static variables in each public class
+     * \param istr Input stream
+     * \return true on success
      */
-    static bool RestoreStaticState(FILE* pf);
+    static bool RestoreStaticState(std::istream &istr);
 
     /**
      * \brief Request a lock on this class (for "synchronized" keyword)
diff --git a/src/CBot/CBotFileUtils.cpp b/src/CBot/CBotFileUtils.cpp
index c473493a..ccde313c 100644
--- a/src/CBot/CBotFileUtils.cpp
+++ b/src/CBot/CBotFileUtils.cpp
@@ -21,129 +21,251 @@
 
 #include "CBot/CBotClass.h"
 #include "CBot/CBotEnums.h"
-#include "CBot/CBotUtils.h"
 
 namespace CBot
 {
 
-
-// file management
-
-// necessary because it is not possible to do the fopen in the main program
-// fwrite and fread in a dll or using the FILE * returned.
-
-////////////////////////////////////////////////////////////////////////////////
-FILE* fOpen(const char* name, const char* mode)
+template<typename T>
+static bool WriteBinary(std::ostream &ostr, T value, unsigned padTo = 0)
 {
-    return fopen(name, mode);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-int fClose(FILE* filehandle)
-{
-    return fclose(filehandle);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-std::size_t fWrite(const void *buffer,
-                   std::size_t elemsize,
-                   std::size_t length,
-                   FILE* filehandle)
-{
-    return fwrite(buffer, elemsize, length, filehandle);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-std::size_t fRead(void *buffer,
-                  std::size_t elemsize,
-                  std::size_t length,
-                  FILE* filehandle)
-{
-    return fread(buffer, elemsize, length, filehandle);
-}
-
-
-////////////////////////////////////////////////////////////////////////////////
-bool ReadWord(FILE* pf, unsigned short& w)
-{
-    size_t  lg;
-
-    lg = fread(&w, sizeof( unsigned short ), 1, pf );
-
-    return (lg == 1);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-bool ReadFloat(FILE* pf, float& w)
-{
-    size_t  lg;
-
-    lg = fread(&w, sizeof( float ), 1, pf );
-
-    return (lg == 1);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-bool WriteLong(FILE* pf, long w)
-{
-    size_t  lg;
-
-    lg = fwrite(&w, sizeof( long ), 1, pf );
-
-    return (lg == 1);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-bool ReadLong(FILE* pf, long& w)
-{
-    size_t  lg;
-
-    lg = fread(&w, sizeof( long ), 1, pf );
-
-    return (lg == 1);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-bool ReadString(FILE* pf, std::string& s)
-{
-    unsigned short  w;
-    char    buf[1000];
-    size_t  lg1, lg2;
-
-    if (!ReadWord(pf, w)) return false;
-    lg1 = w;
-    lg2 = fread(buf, 1, lg1, pf );
-    buf[lg2] = 0;
-
-    s = buf;
-    return (lg1 == lg2);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-bool WriteType(FILE* pf, const CBotTypResult &type)
-{
-    int typ = type.GetType();
-    if ( typ == CBotTypIntrinsic ) typ = CBotTypClass;
-    if ( !WriteWord(pf, typ) ) return false;
-    if ( typ == CBotTypClass )
+    unsigned char chr;
+    unsigned count = 1;
+    while (value > 127) // unsigned LEB128
     {
-        CBotClass* p = type.GetClass();
-        if ( !WriteString(pf, p->GetName()) ) return false;
+        ++count;
+        chr = (value & 0x7F) | 0x80;
+        if (!ostr.write(reinterpret_cast<char*>(&chr), 1)) return false;
+        value >>= 7;
     }
-    if ( type.Eq( CBotTypArrayBody ) ||
-         type.Eq( CBotTypArrayPointer ) )
+    chr = value & 0x7F;
+    if (count < padTo) chr |= 0x80;
+    if (!ostr.write(reinterpret_cast<char*>(&chr), 1)) return false;
+
+    if (count < padTo)
     {
-        if ( !WriteWord(pf, type.GetLimite()) ) return false;
-        if ( !WriteType(pf, type.GetTypElem()) ) return false;
+        while (++count < padTo)
+            if (!(ostr << '\x80')) return false;
+        if (!(ostr << '\x00')) return false;
     }
     return true;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-bool ReadType(FILE* pf, CBotTypResult &type)
+template<typename T>
+static bool ReadBinary(std::istream &istr, T &value)
+{
+    value = 0;
+    unsigned char chr;
+    unsigned shift = 0;
+    while (true)        // unsigned LEB128
+    {
+        if (!istr.read(reinterpret_cast<char*>(&chr), 1)) return false;
+        if (shift < sizeof(T) * 8 - 1)
+            value |= static_cast<T>(chr & 0x7F) << shift;
+        shift += 7;
+        if ((chr & 0x80) == 0) break;
+    }
+    return true;
+}
+
+template<typename T>
+static bool WriteSignedBinary(std::ostream &ostr, T value, unsigned padTo = 0)
+{
+    signed char sign = value >> (8 * sizeof(T) - 1);
+    unsigned count = 0;
+    while (true)        // signed LEB128
+    {
+        ++count;
+        unsigned char chr = value & 0x7F;
+        value >>= 7;
+        if (!(value != sign || ((chr ^ sign) & 0x40) != 0))
+        {
+            if (count < padTo) chr |= 0x80;
+            if (!ostr.write(reinterpret_cast<char*>(&chr), 1)) return false;
+            break;
+        }
+        chr |= 0x80;
+        if (!ostr.put(chr)) return false;
+    }
+
+    if (count < padTo)
+    {
+        char chr = (sign < 0) ? 0x7F : 0x00;
+        while (++count < padTo)
+            if (!ostr.put(chr | 0x80)) return false;
+        if (!ostr.put(chr)) return false;
+    }
+    return true;
+}
+
+template<typename T>
+static bool ReadSignedBinary(std::istream &istr, T &value)
+{
+    value = 0;
+    unsigned char chr;
+    unsigned shift = 0;
+    while (true)        // signed LEB128
+    {
+        if (!istr.read(reinterpret_cast<char*>(&chr), 1)) return false;
+        if (shift < sizeof(T) * 8 - 1)
+            value |= (static_cast<T>(chr & 0x7F) << shift);
+        shift += 7;
+        if ((chr & 0x80) == 0) break;
+    }
+
+    if (shift >= 8 * sizeof(T) - 1) shift = 8 * sizeof(T) - 1;
+    if ((chr & 0x40) != 0)
+        value |= static_cast<T>(-1) << shift;
+
+    return true;
+}
+
+bool WriteWord(std::ostream &ostr, unsigned short w)
+{
+    return WriteBinary<unsigned short>(ostr, w);
+}
+
+bool ReadWord(std::istream &istr, unsigned short &w)
+{
+    return ReadBinary<unsigned short>(istr, w);
+}
+
+bool WriteByte(std::ostream &ostr, char c)
+{
+    if (!ostr.put(c)) return false;
+    return true;
+}
+
+bool ReadByte(std::istream &istr, char& c)
+{
+    if (!istr.get(c)) return false;
+    return true;
+}
+
+bool WriteShort(std::ostream &ostr, short s)
+{
+    return WriteSignedBinary<short>(ostr, s);
+}
+
+bool ReadShort(std::istream &istr, short &s)
+{
+    return ReadSignedBinary<short>(istr, s);
+}
+
+bool WriteInt(std::ostream &ostr, int i)
+{
+    return WriteSignedBinary<int>(ostr, i);
+}
+
+bool ReadInt(std::istream &istr, int &i)
+{
+    return ReadSignedBinary<int>(istr, i);
+}
+
+bool WriteLong(std::ostream &ostr, long l, unsigned padTo)
+{
+    return WriteSignedBinary<long>(ostr, l, padTo);
+}
+
+bool ReadLong(std::istream &istr, long &l)
+{
+    return ReadSignedBinary<long>(istr, l);
+}
+
+bool WriteFloat(std::ostream &ostr, float f)
+{
+    union {float fValue; unsigned int iValue;} u;
+    u.fValue = 0.0f;
+    u.iValue = 0;
+
+    u.fValue = f;
+    return WriteBinary<unsigned int>(ostr, u.iValue);
+}
+
+bool ReadFloat(std::istream &istr, float &f)
+{
+    union {float fValue; unsigned int iValue;} u;
+    u.fValue = 0.0f;
+    u.iValue = 0;
+
+    if (!ReadBinary<unsigned int>(istr, u.iValue)) return false;
+    f = u.fValue;
+    return true;
+}
+
+bool WriteDouble(std::ostream &ostr, double d)
+{
+    union {double dValue; unsigned long iValue;} u;
+    u.dValue = 0.0;
+    u.iValue = 0;
+
+    u.dValue = d;
+    return WriteBinary<unsigned long>(ostr, u.iValue);
+}
+
+bool ReadDouble(std::istream &istr, double &d)
+{
+    union {double dValue; unsigned long iValue;} u;
+    u.dValue = 0.0;
+    u.iValue = 0;
+
+    if (!ReadBinary<unsigned long>(istr, u.iValue)) return false;
+    d = u.dValue;
+    return true;
+}
+
+bool WriteString(std::ostream &ostr, const std::string &s)
+{
+    if (!WriteBinary<size_t>(ostr, s.size())) return false;
+    if (!ostr.write(&(s[0]), s.size())) return false;
+
+    return true;
+}
+
+bool ReadString(std::istream &istr, std::string &s)
+{
+    size_t length = 0;
+    if (!ReadBinary<size_t>(istr, length)) return false;
+
+    s.resize(length);
+    if (length != 0)
+    {
+        if (!istr.read(&(s[0]), length)) return false;
+    }
+    return true;
+}
+
+bool WriteType(std::ostream &ostr, const CBotTypResult &type)
+{
+    int typ = type.GetType();
+    if ( typ == CBotTypIntrinsic ) typ = CBotTypClass;
+    if ( !WriteWord(ostr, typ) ) return false;
+    if ( typ == CBotTypClass )
+    {
+        CBotClass* p = type.GetClass();
+        if (!WriteString(ostr, p->GetName())) return false;
+    }
+    if ( type.Eq( CBotTypArrayBody ) ||
+         type.Eq( CBotTypArrayPointer ) )
+    {
+        if (!WriteWord(ostr, type.GetLimite())) return false;
+        if (!WriteType(ostr, type.GetTypElem())) return false;
+    }
+
+    if ( type.Eq(CBotTypPointer) )
+    {
+        if (type.GetClass() != nullptr)
+        {
+            if (!WriteString(ostr, type.GetClass()->GetName())) return false;
+        }
+        else if (!WriteString(ostr, "")) return false;
+    }
+    return true;
+}
+
+bool ReadType(std::istream &istr, CBotTypResult &type)
 {
     unsigned short  w, ww;
-    if ( !ReadWord(pf, w) ) return false;
+    if (!ReadWord(istr, w)) return false;
     type.SetType(w);
 
     if ( type.Eq( CBotTypIntrinsic ) )
@@ -154,7 +276,7 @@ bool ReadType(FILE* pf, CBotTypResult &type)
     if ( type.Eq( CBotTypClass ) )
     {
         std::string  s;
-        if ( !ReadString(pf, s) ) return false;
+        if (!ReadString(istr, s)) return false;
         type = CBotTypResult( w, s );
     }
 
@@ -162,11 +284,45 @@ bool ReadType(FILE* pf, CBotTypResult &type)
          type.Eq( CBotTypArrayBody ) )
     {
         CBotTypResult   r;
-        if ( !ReadWord(pf, ww) ) return false;
-        if ( !ReadType(pf, r) ) return false;
+        if (!ReadWord(istr, ww)) return false;
+        if (!ReadType(istr, r)) return false;
         type = CBotTypResult( w, r );
         type.SetLimite(static_cast<short>(ww));
     }
+
+    if ( type.Eq(CBotTypPointer) )
+    {
+        std::string className;
+        if (!ReadString(istr, className)) return false;
+        type = CBotTypResult(w, className);
+    }
+    return true;
+}
+
+bool WriteStream(std::ostream &ostr, std::istream& istr)
+{
+    if (!istr.seekg(0, istr.end)) return false;
+    auto size = istr.tellg();
+
+    if (size == 0) return WriteLong(ostr, 0);
+    if (!WriteLong(ostr, size)) return false;
+
+    if (!istr.seekg(0, istr.beg)) return false;
+    if (!(ostr << istr.rdbuf())) return false;
+
+    return true;
+}
+
+bool ReadStream(std::istream& istr, std::ostream &ostr)
+{
+    long length;
+    if (!ReadLong(istr, length)) return false;
+    if (length == 0) return true;
+
+    while (length-- > 0)
+    {
+        if (!(ostr << istr.get())) return false;
+    }
     return true;
 }
 
diff --git a/src/CBot/CBotFileUtils.h b/src/CBot/CBotFileUtils.h
index fec6298a..8f739cb4 100644
--- a/src/CBot/CBotFileUtils.h
+++ b/src/CBot/CBotFileUtils.h
@@ -19,7 +19,7 @@
 
 #pragma once
 
-#include <cstdio>
+#include <iostream>
 #include <string>
 
 namespace CBot
@@ -28,128 +28,173 @@ namespace CBot
 class CBotVar;
 class CBotTypResult;
 
-///////////////////////////////////////////////////////////////////////////////
-// routines for file management  (* FILE)
-
 /*!
- * \brief fOpen
- * \param name
- * \param mode
- * \return
+ * \brief Save a linked list if variables
+ * \param ostr Output stream
+ * \param pVar First variable in the list
+ * \return true on success
  */
-FILE* fOpen(const char* name, const char* mode);
-
-/*!
- * \brief fClose
- * \param filehandle
- * \return
- */
-int fClose(FILE* filehandle);
-
-/*!
- * \brief fWrite
- * \param buffer
- * \param elemsize
- * \param length
- * \param filehandle
- * \return
- */
-std::size_t fWrite(const void *buffer,
-                   std::size_t elemsize,
-                   std::size_t length,
-                   FILE* filehandle);
-
-/*!
- * \brief fRead
- * \param buffer
- * \param elemsize
- * \param length
- * \param filehandle
- * \return
- */
-std::size_t fRead(void *buffer,
-                  std::size_t elemsize,
-                  std::size_t length,
-                  FILE* filehandle);
-
-/*!
- * \brief SaveVars
- * \param pf
- * \param pVar
- * \return
- */
-bool SaveVars(FILE* pf, CBotVar* pVar);
+bool SaveVars(std::ostream &ostr, CBotVar* pVar);
 
 /*!
  * \brief WriteWord
- * \param pf
+ * \param ostr Output stream
  * \param w
- * \return
+ * \return true on success
  */
-bool WriteWord(FILE* pf, unsigned short w);
+bool WriteWord(std::ostream &ostr, unsigned short w);
 
 /*!
  * \brief ReadWord
- * \param pf
- * \param w
- * \return
+ * \param istr Input stream
+ * \param[out] w
+ * \return true on success
  */
-bool ReadWord(FILE* pf, unsigned short& w);
+bool ReadWord(std::istream &istr, unsigned short &w);
 
 /*!
- * \brief ReadLong
- * \param pf
- * \param w
- * \return
+ * \brief WriteByte
+ * \param ostr Output stream
+ * \param c
+ * \return true on success
  */
-bool ReadLong(FILE* pf, long& w);
+bool WriteByte(std::ostream &ostr, char c);
 
 /*!
- * \brief WriteFloat
- * \param pf
- * \param w
- * \return
+ * \brief ReadByte
+ * \param istr Input stream
+ * \param[out] c
+ * \return true on success
  */
-bool WriteFloat(FILE* pf, float w);
+bool ReadByte(std::istream &istr, char& c);
+
+/*!
+ * \brief WriteShort
+ * \param ostr Output stream
+ * \param s
+ * \return true on success
+ */
+bool WriteShort(std::ostream &ostr, short s);
+
+/*!
+ * \brief ReadShort
+ * \param istr Input stream
+ * \param[out] s
+ * \return true on success
+ */
+bool ReadShort(std::istream &istr, short &s);
+
+/*!
+ * \brief WriteInt
+ * \param ostr Output stream
+ * \param i
+ * \return true on success
+ */
+bool WriteInt(std::ostream &ostr, int i);
+
+/*!
+ * \brief ReadInt
+ * \param istr Input stream
+ * \param[out] i
+ * \return true on success
+ */
+bool ReadInt(std::istream &istr, int &i);
 
 /*!
  * \brief WriteLong
- * \param pf
- * \param w
- * \return
+ * \param ostr Output stream
+ * \param l
+ * \param padTo minimum number of bytes to write
+ * \return true on success
  */
-bool WriteLong(FILE* pf, long w);
+bool WriteLong(std::ostream &ostr, long l, unsigned padTo = 0);
+
+/*!
+ * \brief ReadLong
+ * \param istr Input stream
+ * \param[out] l
+ * \return true on success
+ */
+bool ReadLong(std::istream &istr, long &l);
+
+/*!
+ * \brief WriteFloat
+ * \param ostr Output stream
+ * \param f
+ * \return true on success
+ */
+bool WriteFloat(std::ostream &ostr, float f);
 
 /*!
  * \brief ReadFloat
- * \param pf
- * \param w
- * \return
+ * \param istr Input stream
+ * \param[out] f
+ * \return true on success
  */
-bool ReadFloat(FILE* pf, float& w);
+bool ReadFloat(std::istream &istr, float &f);
+
+/*!
+ * \brief WriteDouble
+ * \param ostr Output stream
+ * \param d
+ * \return true on success
+ */
+bool WriteDouble(std::ostream &ostr, double d);
+
+/*!
+ * \brief ReadDouble
+ * \param istr Input stream
+ * \param[out] d
+ * \return true on success
+ */
+bool ReadDouble(std::istream &istr, double &d);
+
+/*!
+ * \brief WriteString
+ * \param ostr Output stream
+ * \param s
+ * \return true on success
+ */
+bool WriteString(std::ostream &ostr, const std::string &s);
 
 /*!
  * \brief ReadString
- * \param pf
- * \param s
- * \return
+ * \param istr Input stream
+ * \param[out] s
+ * \return true on success
  */
-bool ReadString(FILE* pf, std::string& s);
+bool ReadString(std::istream &istr, std::string &s);
 
 /*!
  * \brief WriteType
- * \param pf
+ * \param ostr Output stream
  * \param type
- * \return
+ * \return true on success
  */
-bool WriteType(FILE* pf, const CBotTypResult &type);
+bool WriteType(std::ostream &ostr, const CBotTypResult &type);
 
 /*!
  * \brief ReadType
- * \param pf
- * \param type
- * \return
+ * \param istr Input stream
+ * \param[out] type
+ * \return true on success
  */
-bool ReadType(FILE* pf, CBotTypResult &type);
+bool ReadType(std::istream &istr, CBotTypResult &type);
+
+/*!
+ * \brief WriteStream
+ * \param ostr Output stream
+ * \param istr Input stream
+ * \return true on success
+ */
+bool WriteStream(std::ostream &ostr, std::istream& istr);
+
+/*!
+ * \brief ReadStream
+ * \param istr Input stream
+ * \param ostr Output stream
+ * \return true on success
+ */
+bool ReadStream(std::istream& istr, std::ostream &ostr);
 
 } // namespace CBot
diff --git a/src/CBot/CBotProgram.cpp b/src/CBot/CBotProgram.cpp
index e8065f47..14ec2b2e 100644
--- a/src/CBot/CBotProgram.cpp
+++ b/src/CBot/CBotProgram.cpp
@@ -24,7 +24,6 @@
 #include "CBot/CBotCStack.h"
 #include "CBot/CBotClass.h"
 #include "CBot/CBotUtils.h"
-#include "CBot/CBotFileUtils.h"
 
 #include "CBot/CBotInstr/CBotFunction.h"
 
@@ -332,51 +331,56 @@ bool CBotProgram::DefineNum(const std::string& name, long val)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotProgram::SaveState(FILE* pf)
+bool CBotProgram::SaveState(std::ostream &ostr)
 {
-    if (!WriteWord( pf, CBOTVERSION)) return false;
+    if (!WriteLong(ostr, CBOTVERSION)) return false;
 
 
     if (m_stack != nullptr )
     {
-        if (!WriteWord( pf, 1)) return false;
-        if (!WriteString( pf, m_entryPoint->GetName() )) return false;
-        if (!m_stack->SaveState(pf)) return false;
+        if (!WriteWord(ostr, 1)) return false;
+        if (!WriteString(ostr, m_entryPoint->GetName())) return false;
+        if (!m_stack->SaveState(ostr)) return false;
     }
     else
     {
-        if (!WriteWord( pf, 0)) return false;
+        if (!WriteWord(ostr, 0)) return false;
     }
     return true;
 }
 
-bool CBotProgram::RestoreState(FILE* pf)
+bool CBotProgram::RestoreState(std::istream &istr)
 {
     unsigned short  w;
     std::string      s;
 
     Stop();
 
-    if (!ReadWord( pf, w )) return false;
-    if ( w != CBOTVERSION ) return false;
+    long version;
+    if (!ReadLong(istr, version)) return false;
+    if ( version != CBOTVERSION ) return false;
 
-    if (!ReadWord( pf, w )) return false;
+    if (!ReadWord(istr, w)) return false;
     if ( w == 0 ) return true;
 
-    if (!ReadString( pf, s )) return false;
-    Start(s);       // point de reprise
+    // don't restore if compile error exists
+    if (m_error != CBotNoErr) return false;
 
-    if (m_stack != nullptr)
+    if (!ReadString(istr, s)) return false;
+    if (!Start(s)) return false; // point de reprise
+    // Start() already created the new stack
+    // and called m_stack->SetProgram(this);
+
+    // retrieves the stack from the memory
+    if (!m_stack->RestoreState(istr, m_stack))
     {
         m_stack->Delete();
         m_stack = nullptr;
+        m_stack = CBotStack::AllocateStack(); // start from the top
+        m_stack->SetProgram(this);
+        return false; // signal error
     }
 
-    // retrieves the stack from the memory
-    m_stack = CBotStack::AllocateStack();
-    if (!m_stack->RestoreState(pf, m_stack)) return false;
-    m_stack->SetProgram(this);                     // bases for routines
-
     // restored some states in the stack according to the structure
     m_entryPoint->RestoreState(nullptr, m_stack, m_thisVar);
     return true;
diff --git a/src/CBot/CBotProgram.h b/src/CBot/CBotProgram.h
index e258fff0..c448b82c 100644
--- a/src/CBot/CBotProgram.h
+++ b/src/CBot/CBotProgram.h
@@ -282,27 +282,20 @@ public:
 
     /**
      * \brief Save the current execution status into a file
-     * \param pf
-     * \parblock
-     * file handle
-     *
-     * This file handle must have been opened by this library! Otherwise crashes on Windows
-     *
-     * TODO: Verify this
-     * \endparblock
+     * \param ostr Output stream
      * \return true on success, false on write error
      */
-    bool SaveState(FILE* pf);
+    bool SaveState(std::ostream &ostr);
 
     /**
      * \brief Restore the execution state from a file
      *
      * The previous program code must already have been recompiled with Compile() before calling this function
      *
-     * \param pf file handle
+     * \param istr Input stream
      * \return true on success, false on read error
      */
-    bool RestoreState(FILE* pf);
+    bool RestoreState(std::istream &istr);
 
     /**
      * \brief GetPosition Gives the position of a routine in the original text
diff --git a/src/CBot/CBotStack.cpp b/src/CBot/CBotStack.cpp
index 9f9db2d6..7f3c0b9a 100644
--- a/src/CBot/CBotStack.cpp
+++ b/src/CBot/CBotStack.cpp
@@ -26,7 +26,6 @@
 #include "CBot/CBotVar/CBotVarPointer.h"
 #include "CBot/CBotVar/CBotVarClass.h"
 
-#include "CBot/CBotFileUtils.h"
 #include "CBot/CBotUtils.h"
 #include "CBot/CBotExternalCall.h"
 
@@ -687,108 +686,106 @@ CBotVar* CBotStack::GetStackVars(std::string& functionName, int level)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotStack::SaveState(FILE* pf)
+bool CBotStack::SaveState(std::ostream &ostr)
 {
     if (m_next2 != nullptr)
     {
-        if (!WriteWord(pf, 2)) return false; // a marker of type (m_next2)
-        if (!m_next2->SaveState(pf)) return false; // saves the next element
+        if (!WriteWord(ostr, 2)) return false; // a marker of type (m_next2)
+        if (!m_next2->SaveState(ostr)) return false; // saves the next element
     }
     else
     {
-        if (!WriteWord(pf, 1)) return false; // a marker of type (m_next)
+        if (!WriteWord(ostr, 1)) return false; // a marker of type (m_next)
     }
-    if (!WriteWord(pf, static_cast<unsigned short>(m_block))) return false;
-    if (!WriteWord(pf, m_state)) return false;
-    if (!WriteWord(pf, 0)) return false; // for backwards combatibility (m_bDontDelete)
-    if (!WriteWord(pf, m_step)) return false;
+    if (!WriteWord(ostr, static_cast<unsigned short>(m_block))) return false;
+    if (!WriteInt(ostr, m_state)) return false;
+    if (!WriteWord(ostr, 0)) return false; // for backwards combatibility (m_bDontDelete)
+    if (!WriteInt(ostr, m_step)) return false;
 
-
-    if (!SaveVars(pf, m_var)) return false;            // current result
-    if (!SaveVars(pf, m_listVar)) return false;        // local variables
+    if (!SaveVars(ostr, m_var)) return false;          // current result
+    if (!SaveVars(ostr, m_listVar)) return false;      // local variables
 
     if (m_next != nullptr)
     {
-        if (!m_next->SaveState(pf)) return false; // saves the next element
+        if (!m_next->SaveState(ostr)) return false; // saves the next element
     }
     else
     {
-        if (!WriteWord(pf, 0)) return false; // terminator
+        if (!WriteWord(ostr, 0)) return false; // 0 - CBotStack::SaveState terminator
     }
     return true;
 }
 
-bool SaveVars(FILE* pf, CBotVar* pVar)
+bool SaveVars(std::ostream &ostr, CBotVar* pVar)
 {
     while (pVar != nullptr)
     {
-        if (!pVar->Save0State(pf)) return false; // common header
-        if (!pVar->Save1State(pf)) return false; // saves the data
+        if (!pVar->Save0State(ostr)) return false; // common header
+        if (!pVar->Save1State(ostr)) return false; // saves the data
 
         pVar = pVar->GetNext();
     }
-    return WriteWord(pf, 0); // terminator
+    return WriteWord(ostr, 0); // 0 - CBot::SaveVars terminator
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotStack::RestoreState(FILE* pf, CBotStack* &pStack)
+bool CBotStack::RestoreState(std::istream &istr, CBotStack* &pStack)
 {
     unsigned short w;
 
     if (pStack != this) pStack = nullptr;
-    if (!ReadWord(pf, w)) return false;
-    if ( w == 0 ) return true; // 0 - terminator
+    if (!ReadWord(istr, w)) return false;
+    if ( w == 0 ) return true; // 0 - CBotStack::SaveState terminator
 
     if (pStack == nullptr) pStack = AddStack();
 
     if ( w == 2 ) // 2 - m_next2
     {
-        if (!pStack->RestoreState(pf, pStack->m_next2)) return false;
+        if (!pStack->RestoreState(istr, pStack->m_next2)) return false;
     }
 
-    if (!ReadWord(pf, w)) return false;
+    if (!ReadWord(istr, w)) return false;
     pStack->m_block = static_cast<BlockVisibilityType>(w);
 
-    if (!ReadWord(pf, w)) return false;
-    pStack->SetState(static_cast<short>(w));
+    int state;
+    if (!ReadInt(istr, state)) return false;
+    pStack->SetState(state);
 
-    if (!ReadWord(pf, w)) return false; // backwards compatibility (m_bDontDelete)
+    if (!ReadWord(istr, w)) return false; // backwards compatibility (m_bDontDelete)
 
-    if (!ReadWord(pf, w)) return false;
-    pStack->m_step = w;
+    if (!ReadInt(istr, state)) return false;
+    pStack->m_step = state;
 
-    if (!CBotVar::RestoreState(pf, pStack->m_var)) return false;    // temp variable
-    if (!CBotVar::RestoreState(pf, pStack->m_listVar)) return false;// local variables
+    if (!CBotVar::RestoreState(istr, pStack->m_var)) return false;     // temp variable
+    if (!CBotVar::RestoreState(istr, pStack->m_listVar)) return false; // local variables
 
-    return pStack->RestoreState(pf, pStack->m_next);
+    return pStack->RestoreState(istr, pStack->m_next);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotVar::Save0State(FILE* pf)
+bool CBotVar::Save0State(std::ostream &ostr)
 {
-    if (!WriteWord(pf, 100+static_cast<int>(m_mPrivate)))return false;        // private variable?
-    if (!WriteWord(pf, m_bStatic))return false;                // static variable?
-    if (!WriteWord(pf, m_type.GetType()))return false;        // saves the type (always non-zero)
+    if (!WriteWord(ostr, 100+static_cast<int>(m_mPrivate)))return false; // private variable?
+    if (!WriteWord(ostr, m_bStatic))return false;            // static variable?
+    if (!WriteWord(ostr, m_type.GetType()))return false;     // saves the type (always non-zero)
 
     if (m_type.Eq(CBotTypPointer) && GetPointer() != nullptr)
     {
         if (GetPointer()->m_bConstructor)                    // constructor was called?
         {
-            if (!WriteWord(pf, (2000 + static_cast<unsigned short>(m_binit)) )) return false;
-            return WriteString(pf, m_token->GetString());    // and variable name
+            if (!WriteWord(ostr, (2000 + static_cast<unsigned short>(m_binit)) )) return false;
+            return WriteString(ostr, m_token->GetString());  // and variable name
         }
     }
 
-    if (!WriteWord(pf, static_cast<unsigned short>(m_binit))) return false;          // variable defined?
-    return WriteString(pf, m_token->GetString());            // and variable name
+    if (!WriteWord(ostr, static_cast<unsigned short>(m_binit))) return false;        // variable defined?
+    return WriteString(ostr, m_token->GetString());          // and variable name
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotVar::RestoreState(FILE* pf, CBotVar* &pVar)
+bool CBotVar::RestoreState(std::istream &istr, CBotVar* &pVar)
 {
     unsigned short        w, wi, prv, st;
-    float        ww;
-    std::string    name, s;
 
     delete pVar;
 
@@ -798,27 +795,27 @@ bool CBotVar::RestoreState(FILE* pf, CBotVar* &pVar)
 
     while ( true )            // retrieves a list
     {
-        if (!ReadWord(pf, w)) return false;                        // private or type?
-        if ( w == 0 ) return true;
+        if (!ReadWord(istr, w)) return false;                      // private or type?
+        if ( w == 0 ) return true; // 0 - CBot::SaveVars terminator
 
         std::string defnum;
         if ( w == 200 )
         {
-            if (!ReadString(pf, defnum)) return false;            // number with identifier
-            if (!ReadWord(pf, w)) return false;                    // type
+            if (!ReadString(istr, defnum)) return false;          // number with identifier
+            if (!ReadWord(istr, w)) return false;                 // type
         }
 
         prv = 100; st = 0;
         if ( w >= 100 )
         {
             prv = w;
-            if (!ReadWord(pf, st)) return false;                // static
-            if (!ReadWord(pf, w)) return false;                    // type
+            if (!ReadWord(istr, st)) return false;              // static
+            if (!ReadWord(istr, w)) return false;               // type
         }
 
         if ( w == CBotTypClass ) w = CBotTypIntrinsic;            // necessarily intrinsic
 
-        if (!ReadWord(pf, wi)) return false;                    // init ?
+        if (!ReadWord(istr, wi)) return false;                  // init ?
         bool bConstructor = false;
         if (w == CBotTypPointer && wi >= 2000)
         {
@@ -827,31 +824,40 @@ bool CBotVar::RestoreState(FILE* pf, CBotVar* &pVar)
         }
 
         CBotVar::InitType initType = static_cast<CBotVar::InitType>(wi);
-        if (!ReadString(pf, name)) return false;                // variable name
-
-        CBotToken token(name, std::string());
+        std::string varname;
+        if (!ReadString(istr, varname)) return false;           // variable name
+        CBotToken token(varname, std::string());
 
         bool isClass = false;
 
         switch (w)
         {
-        case CBotTypInt:
         case CBotTypBoolean:
+            char valByte;
+            if (!ReadByte(istr, valByte)) return false;
             pNew = CBotVar::Create(token, w);                        // creates a variable
-            if (!ReadWord(pf, w)) return false;
-            pNew->SetValInt(static_cast<short>(w), defnum);
+            pNew->SetValInt(valByte);
+            break;
+        case CBotTypInt:
+            int valInt;
+            if (!ReadInt(istr, valInt)) return false;
+            pNew = CBotVar::Create(token, w);                        // creates a variable
+            pNew->SetValInt(valInt, defnum);
             break;
         case CBotTypFloat:
+            float valFloat;
+            if (!ReadFloat(istr, valFloat)) return false;
             pNew = CBotVar::Create(token, w);                        // creates a variable
-            if (!ReadFloat(pf, ww)) return false;
-            pNew->SetValFloat(ww);
+            pNew->SetValFloat(valFloat);
             break;
         case CBotTypString:
-            pNew = CBotVar::Create(token, w);                        // creates a variable
-            if (!ReadString(pf, s)) return false;
-            pNew->SetValString(s);
-            break;
-
+            {
+                std::string valString;
+                if (!ReadString(istr, valString)) return false;
+                pNew = CBotVar::Create(token, w);                    // creates a variable
+                pNew->SetValString(valString);
+                break;
+            }
         // returns an intrinsic object or element of an array
         case CBotTypIntrinsic:
             isClass = true;
@@ -859,17 +865,16 @@ bool CBotVar::RestoreState(FILE* pf, CBotVar* &pVar)
             {
                 CBotTypResult    r;
                 long            id;
-                if (!ReadType(pf, r))  return false;                // complete type
-                if (!ReadLong(pf, id) ) return false;
+                if (!ReadType(istr, r)) return false;               // complete type
+                if (!ReadLong(istr, id)) return false;
 
-//                if (!ReadString(pf, s)) return false;
                 {
                     CBotVar* p = nullptr;
                     if ( id ) p = CBotVarClass::Find(id) ;
 
                     pNew = new CBotVarClass(token, r);                // directly creates an instance
                                                                     // attention cptuse = 0
-                    if ( !RestoreState(pf, (static_cast<CBotVarClass*>(pNew))->m_pVar)) return false;
+                    if (!RestoreState(istr, (static_cast<CBotVarClass*>(pNew))->m_pVar)) return false;
                     pNew->SetIdent(id);
 
                     if (isClass && p == nullptr) // set id for each item in this instance
@@ -895,18 +900,20 @@ bool CBotVar::RestoreState(FILE* pf, CBotVar* &pVar)
 
         case CBotTypPointer:
         case CBotTypNullPointer:
-            if (!ReadString(pf, s)) return false;   // name of the class
+        {
+            std::string className;
+            if (!ReadString(istr, className)) return false; // name of the class
             {
-                CBotTypResult ptrType(w, s);
-                pNew = CBotVar::Create(token, ptrType);// creates a variable
 //                CBotVarClass* p = nullptr;
                 long id;
-                ReadLong(pf, id);
+                if (!ReadLong(istr, id)) return false;
 //                if ( id ) p = CBotVarClass::Find(id);        // found the instance (made by RestoreInstance)
 
+                CBotTypResult ptrType(w, className);
+                pNew = CBotVar::Create(token, ptrType);        // creates a variable
                 // returns a copy of the original instance
                 CBotVar* pInstance = nullptr;
-                if ( !CBotVar::RestoreState( pf, pInstance ) ) return false;
+                if (!CBotVar::RestoreState(istr, pInstance)) return false;
                 (static_cast<CBotVarPointer*>(pNew))->SetPointer( pInstance );            // and point over
 
                 if (bConstructor) pNew->ConstructorSet(); // constructor was called
@@ -916,22 +923,22 @@ bool CBotVar::RestoreState(FILE* pf, CBotVar* &pVar)
 
             }
             break;
-
+        }
         case CBotTypArrayPointer:
             {
                 CBotTypResult    r;
-                if (!ReadType(pf, r))  return false;
+                if (!ReadType(istr, r)) return false;
 
                 pNew = CBotVar::Create(token, r);                        // creates a variable
 
                 // returns a copy of the original instance
                 CBotVar* pInstance = nullptr;
-                if ( !CBotVar::RestoreState( pf, pInstance ) ) return false;
+                if (!CBotVar::RestoreState(istr, pInstance)) return false;
                 (static_cast<CBotVarPointer*>(pNew))->SetPointer( pInstance );            // and point over
             }
             break;
         default:
-            assert(0);
+            return false; // signal error
         }
 
         if ( pPrev != nullptr ) pPrev->m_next = pNew;
diff --git a/src/CBot/CBotStack.h b/src/CBot/CBotStack.h
index a72b3e4a..498ccd78 100644
--- a/src/CBot/CBotStack.h
+++ b/src/CBot/CBotStack.h
@@ -434,8 +434,8 @@ public:
     //! \name Write to file
     //@{
 
-    bool            SaveState(FILE* pf);
-    bool            RestoreState(FILE* pf, CBotStack* &pStack);
+    bool            SaveState(std::ostream &ostr);
+    bool            RestoreState(std::istream &istr, CBotStack* &pStack);
 
     //@}
 
diff --git a/src/CBot/CBotUtils.cpp b/src/CBot/CBotUtils.cpp
index a6c6ef9c..a87e2943 100644
--- a/src/CBot/CBotUtils.cpp
+++ b/src/CBot/CBotUtils.cpp
@@ -108,38 +108,6 @@ CBotTypResult ArrayType(CBotToken* &p, CBotCStack* pile, CBotTypResult type)
     return type;
 }
 
-////////////////////////////////////////////////////////////////////////////////
-bool WriteWord(FILE* pf, unsigned short w)
-{
-    size_t  lg;
-
-    lg = fwrite(&w, sizeof( unsigned short ), 1, pf );
-
-    return (lg == 1);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-bool WriteString(FILE* pf, std::string s)
-{
-    size_t  lg1, lg2;
-
-    lg1 = s.size();
-    if (!WriteWord(pf, lg1)) return false;
-
-    lg2 = fwrite(s.c_str(), 1, lg1, pf );
-    return (lg1 == lg2);
-}
-
-////////////////////////////////////////////////////////////////////////////////
-bool WriteFloat(FILE* pf, float w)
-{
-    size_t  lg;
-
-    lg = fwrite(&w, sizeof( float ), 1, pf );
-
-    return (lg == 1);
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 long GetNumInt(const std::string& str)
 {
diff --git a/src/CBot/CBotUtils.h b/src/CBot/CBotUtils.h
index 9042b0f8..5b58535c 100644
--- a/src/CBot/CBotUtils.h
+++ b/src/CBot/CBotUtils.h
@@ -19,9 +19,8 @@
 
 #pragma once
 
-#include "CBot/CBotTypResult.h"
+#include "CBot/CBotFileUtils.h"
 
-#include <cstdio>
 #include <string>
 #include <cassert>
 
@@ -31,6 +30,8 @@ namespace CBot
 class CBotVar;
 class CBotToken;
 class CBotCStack;
+class CBotTypResult;
+
 
 /*!
  * \brief MakeListVars Transforms the array of pointers to variables in a
@@ -58,30 +59,6 @@ CBotTypResult TypeParam(CBotToken* &p, CBotCStack* pile);
  */
 CBotTypResult ArrayType(CBotToken* &p, CBotCStack* pile, CBotTypResult type);
 
-/*!
- * \brief WriteWord
- * \param pf
- * \param w
- * \return
- */
-bool WriteWord(FILE* pf, unsigned short w);
-
-/*!
- * \brief WriteString
- * \param pf
- * \param s
- * \return
- */
-bool WriteString(FILE* pf, std::string s);
-
-/*!
- * \brief WriteFloat
- * \param pf
- * \param w
- * \return
- */
-bool WriteFloat(FILE* pf, float w);
-
 /*!
  * \brief GetNumInt Converts a string into integer may be of the form 0xabc123.
  * \param str
diff --git a/src/CBot/CBotVar/CBotVar.cpp b/src/CBot/CBotVar/CBotVar.cpp
index 62ba41f4..4886c033 100644
--- a/src/CBot/CBotVar/CBotVar.cpp
+++ b/src/CBot/CBotVar/CBotVar.cpp
@@ -134,7 +134,7 @@ void* CBotVar::GetUserPtr()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotVar::Save1State(FILE* pf)
+bool CBotVar::Save1State(std::ostream &ostr)
 {
     // this routine "virtual" must never be called,
     // there must be a routine for each of the subclasses (CBotVarInt, CBotVarFloat, etc)
diff --git a/src/CBot/CBotVar/CBotVar.h b/src/CBot/CBotVar/CBotVar.h
index d2805ddf..980b8a71 100644
--- a/src/CBot/CBotVar/CBotVar.h
+++ b/src/CBot/CBotVar/CBotVar.h
@@ -623,28 +623,28 @@ public:
 
     /**
      * \brief Save common variable header (name, type, etc.)
-     * \param pf file pointer
+     * \param ostr Output stream
      * \return false on write error
      */
-    virtual bool Save0State(FILE* pf);
+    virtual bool Save0State(std::ostream &ostr);
 
     /**
      * \brief Save variable data
      *
      * Overriden in child classes
      *
-     * \param pf file pointer
+     * \param ostr Output stream
      * \return false on write error
      */
-    virtual bool Save1State(FILE* pf);
+    virtual bool Save1State(std::ostream &ostr);
 
     /**
      * \brief Restore variable
-     * \param pf file pointer
+     * \param istr Input stream
      * \param[out] pVar Pointer to recieve the variable
      * \return false on read error
      */
-    static bool RestoreState(FILE* pf, CBotVar* &pVar);
+    static bool RestoreState(std::istream &istr, CBotVar* &pVar);
 
     //@}
 
diff --git a/src/CBot/CBotVar/CBotVarArray.cpp b/src/CBot/CBotVar/CBotVarArray.cpp
index 6462d119..05575dc1 100644
--- a/src/CBot/CBotVar/CBotVarArray.cpp
+++ b/src/CBot/CBotVar/CBotVarArray.cpp
@@ -20,7 +20,6 @@
 #include "CBot/CBotVar/CBotVarArray.h"
 #include "CBot/CBotVar/CBotVarClass.h"
 #include "CBot/CBotToken.h"
-#include "CBot/CBotFileUtils.h"
 
 #include "CBot/CBotEnums.h"
 
@@ -137,10 +136,10 @@ std::string CBotVarArray::GetValString()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotVarArray::Save1State(FILE* pf)
+bool CBotVarArray::Save1State(std::ostream &ostr)
 {
-    if ( !WriteType(pf, m_type) ) return false;
-    return SaveVars(pf, m_pInstance);                        // saves the instance that manages the table
+    if (!WriteType(ostr, m_type)) return false;
+    return SaveVars(ostr, m_pInstance);                      // saves the instance that manages the table
 }
 
 } // namespace CBot
diff --git a/src/CBot/CBotVar/CBotVarArray.h b/src/CBot/CBotVar/CBotVarArray.h
index 68b00b28..fb211055 100644
--- a/src/CBot/CBotVar/CBotVarArray.h
+++ b/src/CBot/CBotVar/CBotVarArray.h
@@ -51,7 +51,7 @@ public:
 
     std::string GetValString() override;
 
-    bool Save1State(FILE* pf) override;
+    bool Save1State(std::ostream &ostr) override;
 
 private:
     //! Array data
diff --git a/src/CBot/CBotVar/CBotVarBoolean.cpp b/src/CBot/CBotVar/CBotVarBoolean.cpp
index d36de078..b733e933 100644
--- a/src/CBot/CBotVar/CBotVarBoolean.cpp
+++ b/src/CBot/CBotVar/CBotVarBoolean.cpp
@@ -40,9 +40,9 @@ void CBotVarBoolean::Not()
     SetValInt(!GetValInt());
 }
 
-bool CBotVarBoolean::Save1State(FILE* pf)
+bool CBotVarBoolean::Save1State(std::ostream &ostr)
 {
-    return WriteWord(pf, m_val);                            // the value of the variable
+    return WriteByte(ostr, m_val);                          // the value of the variable
 }
 
 } // namespace CBot
diff --git a/src/CBot/CBotVar/CBotVarBoolean.h b/src/CBot/CBotVar/CBotVarBoolean.h
index 44774a9f..da810e98 100644
--- a/src/CBot/CBotVar/CBotVarBoolean.h
+++ b/src/CBot/CBotVar/CBotVarBoolean.h
@@ -37,7 +37,7 @@ public:
     void XOr(CBotVar* left, CBotVar* right) override;
     void Not() override;
 
-    bool Save1State(FILE* pf) override;
+    bool Save1State(std::ostream &ostr) override;
 };
 
 } // namespace CBot
diff --git a/src/CBot/CBotVar/CBotVarClass.cpp b/src/CBot/CBotVar/CBotVarClass.cpp
index 36952d18..9d587c1f 100644
--- a/src/CBot/CBotVar/CBotVarClass.cpp
+++ b/src/CBot/CBotVar/CBotVarClass.cpp
@@ -23,8 +23,6 @@
 #include "CBot/CBotStack.h"
 #include "CBot/CBotDefines.h"
 
-#include "CBot/CBotFileUtils.h"
-
 #include "CBot/CBotInstr/CBotInstr.h"
 
 #include <cassert>
@@ -464,12 +462,12 @@ bool CBotVarClass::Ne(CBotVar* left, CBotVar* right)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotVarClass::Save1State(FILE* pf)
+bool CBotVarClass::Save1State(std::ostream &ostr)
 {
-    if ( !WriteType(pf, m_type) ) return false;
-    if ( !WriteLong(pf, m_ItemIdent) ) return false;
+    if (!WriteType(ostr, m_type)) return false;
+    if (!WriteLong(ostr, m_ItemIdent)) return false;
 
-    return SaveVars(pf, m_pVar);                                // content of the object
+    return SaveVars(ostr, m_pVar);                              // content of the object
 }
 
 } // namespace CBot
diff --git a/src/CBot/CBotVar/CBotVarClass.h b/src/CBot/CBotVar/CBotVarClass.h
index 55bdd891..34ec732e 100644
--- a/src/CBot/CBotVar/CBotVarClass.h
+++ b/src/CBot/CBotVar/CBotVarClass.h
@@ -54,7 +54,7 @@ public:
     CBotVar* GetItemList() override;
     std::string GetValString() override;
 
-    bool Save1State(FILE* pf) override;
+    bool Save1State(std::ostream &ostr) override;
 
     void Update(void* pUser) override;
 
diff --git a/src/CBot/CBotVar/CBotVarFloat.cpp b/src/CBot/CBotVar/CBotVarFloat.cpp
index a1c4217f..bfa1c1f9 100644
--- a/src/CBot/CBotVar/CBotVarFloat.cpp
+++ b/src/CBot/CBotVar/CBotVarFloat.cpp
@@ -22,9 +22,9 @@
 namespace CBot
 {
 
-bool CBotVarFloat::Save1State(FILE* pf)
+bool CBotVarFloat::Save1State(std::ostream &ostr)
 {
-    return WriteFloat(pf, m_val); // the value of the variable
+    return WriteFloat(ostr, m_val); // the value of the variable
 }
 
 } // namespace CBot
diff --git a/src/CBot/CBotVar/CBotVarFloat.h b/src/CBot/CBotVar/CBotVarFloat.h
index 81cbcde0..dfdecd9b 100644
--- a/src/CBot/CBotVar/CBotVarFloat.h
+++ b/src/CBot/CBotVar/CBotVarFloat.h
@@ -32,7 +32,7 @@ class CBotVarFloat : public CBotVarNumber<float, CBotTypFloat>
 public:
     CBotVarFloat(const CBotToken &name) : CBotVarNumber(name) {}
 
-    bool Save1State(FILE* pf) override;
+    bool Save1State(std::ostream &ostr) override;
 };
 
 } // namespace CBot
diff --git a/src/CBot/CBotVar/CBotVarInt.cpp b/src/CBot/CBotVar/CBotVarInt.cpp
index 477629ae..852566f9 100644
--- a/src/CBot/CBotVar/CBotVarInt.cpp
+++ b/src/CBot/CBotVar/CBotVarInt.cpp
@@ -45,17 +45,17 @@ std::string CBotVarInt::GetValString()
 void CBotVarInt::Neg()
 {
     CBotVarNumber::Neg();
-    m_defnum.empty();
+    m_defnum.clear();
 }
 void CBotVarInt::Inc()
 {
     CBotVarNumber::Inc();
-    m_defnum.empty();
+    m_defnum.clear();
 }
 void CBotVarInt::Dec()
 {
     CBotVarNumber::Dec();
-    m_defnum.empty();
+    m_defnum.clear();
 }
 
 void CBotVarInt::XOr(CBotVar* left, CBotVar* right)
@@ -90,22 +90,23 @@ void CBotVarInt::SR(CBotVar* left, CBotVar* right)
 void CBotVarInt::Not()
 {
     m_val = ~m_val;
+    m_defnum.clear();
 }
 
-bool CBotVarInt::Save0State(FILE* pf)
+bool CBotVarInt::Save0State(std::ostream &ostr)
 {
     if (!m_defnum.empty())
     {
-        if(!WriteWord(pf, 200)) return false; // special marker
-        if(!WriteString(pf, m_defnum)) return false;
+        if(!WriteWord(ostr, 200)) return false; // special marker
+        if(!WriteString(ostr, m_defnum)) return false;
     }
 
-    return CBotVar::Save0State(pf);
+    return CBotVar::Save0State(ostr);
 }
 
-bool CBotVarInt::Save1State(FILE* pf)
+bool CBotVarInt::Save1State(std::ostream &ostr)
 {
-    return WriteWord(pf, m_val);
+    return WriteInt(ostr, m_val);
 }
 
 } // namespace CBot
diff --git a/src/CBot/CBotVar/CBotVarInt.h b/src/CBot/CBotVar/CBotVarInt.h
index 906a402d..5e04135c 100644
--- a/src/CBot/CBotVar/CBotVarInt.h
+++ b/src/CBot/CBotVar/CBotVarInt.h
@@ -50,8 +50,8 @@ public:
     void SR(CBotVar* left, CBotVar* right) override;
     void ASR(CBotVar* left, CBotVar* right) override;
 
-    bool Save0State(FILE* pf) override;
-    bool Save1State(FILE* pf) override;
+    bool Save0State(std::ostream &ostr) override;
+    bool Save1State(std::ostream &ostr) override;
 
 protected:
     //! The name if given by DefineNum.
diff --git a/src/CBot/CBotVar/CBotVarPointer.cpp b/src/CBot/CBotVar/CBotVarPointer.cpp
index 2f78c90a..24f9a5cb 100644
--- a/src/CBot/CBotVar/CBotVarPointer.cpp
+++ b/src/CBot/CBotVar/CBotVarPointer.cpp
@@ -24,7 +24,6 @@
 
 #include "CBot/CBotEnums.h"
 #include "CBot/CBotUtils.h"
-#include "CBot/CBotFileUtils.h"
 
 #include <cassert>
 
@@ -171,21 +170,21 @@ CBotClass* CBotVarPointer::GetClass()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-bool CBotVarPointer::Save1State(FILE* pf)
+bool CBotVarPointer::Save1State(std::ostream &ostr)
 {
     if ( m_type.GetClass() != nullptr )
     {
-        if (!WriteString(pf, m_type.GetClass()->GetName())) return false;    // name of the class
+        if (!WriteString(ostr, m_type.GetClass()->GetName())) return false;  // name of the class
     }
     else
     {
-        if (!WriteString(pf, "")) return false;
+        if (!WriteString(ostr, "")) return false;
     }
 
-    if (!WriteLong(pf, GetIdent())) return false;        // the unique reference
+    if (!WriteLong(ostr, GetIdent())) return false;      // the unique reference
 
     // also saves the proceedings copies
-    return SaveVars(pf, GetPointer());
+    return SaveVars(ostr, GetPointer());
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/CBot/CBotVar/CBotVarPointer.h b/src/CBot/CBotVar/CBotVarPointer.h
index 75c9bc98..6f9c0155 100644
--- a/src/CBot/CBotVar/CBotVarPointer.h
+++ b/src/CBot/CBotVar/CBotVarPointer.h
@@ -61,7 +61,7 @@ public:
 
     void ConstructorSet() override;
 
-    bool Save1State(FILE* pf) override;
+    bool Save1State(std::ostream &ostr) override;
 
     void Update(void* pUser) override;
 
diff --git a/src/CBot/CBotVar/CBotVarString.cpp b/src/CBot/CBotVar/CBotVarString.cpp
index 91a0e618..90856b82 100644
--- a/src/CBot/CBotVar/CBotVarString.cpp
+++ b/src/CBot/CBotVar/CBotVarString.cpp
@@ -37,9 +37,9 @@ bool CBotVarString::Ne(CBotVar* left, CBotVar* right)
     return left->GetValString() != right->GetValString();
 }
 
-bool CBotVarString::Save1State(FILE* pf)
+bool CBotVarString::Save1State(std::ostream &ostr)
 {
-    return WriteString(pf, m_val);
+    return WriteString(ostr, m_val);
 }
 
 } // namespace CBot
diff --git a/src/CBot/CBotVar/CBotVarString.h b/src/CBot/CBotVar/CBotVarString.h
index d01a80f6..ac04a310 100644
--- a/src/CBot/CBotVar/CBotVarString.h
+++ b/src/CBot/CBotVar/CBotVarString.h
@@ -63,7 +63,7 @@ public:
     bool Eq(CBotVar* left, CBotVar* right) override;
     bool Ne(CBotVar* left, CBotVar* right) override;
 
-    bool Save1State(FILE* pf) override;
+    bool Save1State(std::ostream &ostr) override;
 
 private:
     template<typename T>
diff --git a/src/CBot/CBotVar/CBotVarValue.h b/src/CBot/CBotVar/CBotVarValue.h
index 76e820e8..5e58075d 100644
--- a/src/CBot/CBotVar/CBotVarValue.h
+++ b/src/CBot/CBotVar/CBotVarValue.h
@@ -86,7 +86,10 @@ template <typename T, CBotType type>
 class CBotVarNumberBase : public CBotVarValue<T, type>
 {
 public:
-    CBotVarNumberBase(const CBotToken &name) : CBotVarValue<T, type>(name) {}
+    CBotVarNumberBase(const CBotToken &name) : CBotVarValue<T, type>(name)
+    {
+        this->m_val = static_cast<T>(0);
+    }
 
     void SetValInt(int val, const std::string &s = "") override
     {
diff --git a/src/level/robotmain.cpp b/src/level/robotmain.cpp
index 58d90541..dea86bcb 100644
--- a/src/level/robotmain.cpp
+++ b/src/level/robotmain.cpp
@@ -4449,10 +4449,8 @@ void CRobotMain::SaveOneScript(CObject *obj)
 }
 
 //! Saves the stack of the program in execution of a robot
-bool CRobotMain::SaveFileStack(CObject *obj, FILE *file, int objRank)
+bool CRobotMain::SaveFileStack(CObject *obj, std::ostream &ostr)
 {
-    if (objRank == -1) return true;
-
     if (! obj->Implements(ObjectInterfaceType::Programmable)) return true;
 
     CProgrammableObject* programmable = dynamic_cast<CProgrammableObject*>(obj);
@@ -4460,14 +4458,24 @@ bool CRobotMain::SaveFileStack(CObject *obj, FILE *file, int objRank)
     ObjectType type = obj->GetType();
     if (type == OBJECT_HUMAN) return true;
 
-    return programmable->WriteStack(file);
+    long status = 1;
+    std::stringstream sstr("");
+
+    if (!programmable->WriteStack(sstr))
+    {
+        GetLogger()->Error("WriteStack failed at object id = %i\n", obj->GetID());
+        status = 100; // marked bad
+    }
+
+    if (!CBot::WriteLong(ostr, status)) return false;
+    if (!CBot::WriteStream(ostr, sstr)) return false;
+
+    return true;
 }
 
 //! Resumes the execution stack of the program in a robot
-bool CRobotMain::ReadFileStack(CObject *obj, FILE *file, int objRank)
+bool CRobotMain::ReadFileStack(CObject *obj, std::istream &istr)
 {
-    if (objRank == -1) return true;
-
     if (! obj->Implements(ObjectInterfaceType::Programmable)) return true;
 
     CProgrammableObject* programmable = dynamic_cast<CProgrammableObject*>(obj);
@@ -4475,7 +4483,29 @@ bool CRobotMain::ReadFileStack(CObject *obj, FILE *file, int objRank)
     ObjectType type = obj->GetType();
     if (type == OBJECT_HUMAN) return true;
 
-    return programmable->ReadStack(file);
+    long status;
+    if (!CBot::ReadLong(istr, status)) return false;
+
+    if (status == 100) // was marked bad ?
+    {
+        if (!CBot::ReadLong(istr, status)) return false;
+        if (!istr.seekg(status, istr.cur)) return false;
+        return true; // next program
+    }
+
+    if (status == 1)
+    {
+        std::stringstream sstr("");
+        if (!CBot::ReadStream(istr, sstr)) return false;
+
+        if (!programmable->ReadStack(sstr))
+        {
+            GetLogger()->Error("ReadStack failed at object id = %i\n", obj->GetID());
+        }
+        return true; // next program
+    }
+
+    return false; // error: status == ??
 }
 
 std::vector<std::string> CRobotMain::GetNewScriptNames(ObjectType type)
@@ -4670,25 +4700,36 @@ bool CRobotMain::IOWriteScene(std::string filename, std::string filecbot, std::s
     }
 
     // Writes the file of stacks of execution.
-    FILE* file = CBot::fOpen((CResourceManager::GetSaveLocation() + "/" + filecbot).c_str(), "wb");
-    if (file == nullptr) return false;
+    COutputStream ostr(filecbot);
+    if (!ostr.is_open()) return false;
 
+    bool bError = false;
     long version = 1;
-    CBot::fWrite(&version, sizeof(long), 1, file);  // version of COLOBOT
+    CBot::WriteLong(ostr, version);                 // version of COLOBOT
     version = CBot::CBotProgram::GetVersion();
-    CBot::fWrite(&version, sizeof(long), 1, file);  // version of CBOT
+    CBot::WriteLong(ostr, version);                 // version of CBOT
+    CBot::WriteWord(ostr, 0); // TODO
 
-    objRank = 0;
     for (CObject* obj : m_objMan->GetAllObjects())
     {
         if (obj->GetType() == OBJECT_TOTO) continue;
         if (IsObjectBeingTransported(obj)) continue;
         if (obj->Implements(ObjectInterfaceType::Destroyable) && dynamic_cast<CDestroyableObject*>(obj)->IsDying()) continue;
 
-        if (!SaveFileStack(obj, file, objRank++))  break;
+        if (!SaveFileStack(obj, ostr))
+        {
+            GetLogger()->Error("SaveFileStack failed at object id = %i\n", obj->GetID());
+            bError = true;
+            break;
+        }
     }
-    CBot::CBotClass::SaveStaticState(file);
-    CBot::fClose(file);
+
+    if (!bError && !CBot::CBotClass::SaveStaticState(ostr))
+    {
+        GetLogger()->Error("CBotClass save static state failed\n");
+    }
+
+    ostr.close();
 
     if (!emergencySave)
     {
@@ -4846,29 +4887,48 @@ CObject* CRobotMain::IOReadScene(std::string filename, std::string filecbot)
     m_ui->GetLoadingScreen()->SetProgress(0.95f, RT_LOADING_CBOT_SAVE);
 
     // Reads the file of stacks of execution.
-    FILE* file = CBot::fOpen((CResourceManager::GetSaveLocation() + "/" + filecbot).c_str(), "rb");
-    if (file != nullptr)
+    CInputStream istr(filecbot);
+
+    if (istr.is_open())
     {
-        long version;
-        CBot::fRead(&version, sizeof(long), 1, file);  // version of COLOBOT
+        bool bError = false;
+        long version = 0;
+        CBot::ReadLong(istr, version);             // version of COLOBOT
         if (version == 1)
         {
-            CBot::fRead(&version, sizeof(long), 1, file);  // version of CBOT
+            CBot::ReadLong(istr, version);         // version of CBOT
             if (version == CBot::CBotProgram::GetVersion())
             {
-                objRank = 0;
-                for (CObject* obj : m_objMan->GetAllObjects())
+                unsigned short flag;
+                CBot::ReadWord(istr, flag); // TODO
+                bError = (flag != 0);
+
+                if (!bError) for (CObject* obj : m_objMan->GetAllObjects())
                 {
                     if (obj->GetType() == OBJECT_TOTO) continue;
                     if (IsObjectBeingTransported(obj)) continue;
                     if (obj->Implements(ObjectInterfaceType::Destroyable) && dynamic_cast<CDestroyableObject*>(obj)->IsDying()) continue;
 
-                    if (!ReadFileStack(obj, file, objRank++)) break;
+                    if (!ReadFileStack(obj, istr))
+                    {
+                        GetLogger()->Error("ReadFileStack failed at object id = %i\n", obj->GetID());
+                        bError = true;
+                        break;
+                    }
+                }
+
+                if (!bError && !CBot::CBotClass::RestoreStaticState(istr))
+                {
+                    GetLogger()->Error("CBotClass restore static state failed\n");
+                    bError = true;
                 }
             }
+            else
+                GetLogger()->Error("cbot.run file is wrong version: %i\n", version);
         }
-        CBot::CBotClass::RestoreStaticState(file);
-        CBot::fClose(file);
+
+        if (bError) GetLogger()->Error("Restoring CBOT state failed at stream position: %li\n", istr.tellg());
+        istr.close();
     }
 
     m_ui->GetLoadingScreen()->SetProgress(1.0f, RT_LOADING_FINISHED);
diff --git a/src/level/robotmain.h b/src/level/robotmain.h
index 2614f2cc..2b4c7b03 100644
--- a/src/level/robotmain.h
+++ b/src/level/robotmain.h
@@ -308,8 +308,8 @@ public:
 
     void        SaveAllScript();
     void        SaveOneScript(CObject *obj);
-    bool        SaveFileStack(CObject *obj, FILE *file, int objRank);
-    bool        ReadFileStack(CObject *obj, FILE *file, int objRank);
+    bool        SaveFileStack(CObject *obj, std::ostream &ostr);
+    bool        ReadFileStack(CObject *obj, std::istream &istr);
 
     //! Return list of scripts to load to robot created in BotFactory
     std::vector<std::string> GetNewScriptNames(ObjectType type);
diff --git a/src/object/implementation/programmable_impl.cpp b/src/object/implementation/programmable_impl.cpp
index 5e370bdb..34be6c59 100644
--- a/src/object/implementation/programmable_impl.cpp
+++ b/src/object/implementation/programmable_impl.cpp
@@ -143,24 +143,43 @@ bool CProgrammableObjectImpl::IsProgram()
 
 // Load a stack of script implementation from a file.
 
-bool CProgrammableObjectImpl::ReadStack(FILE *file)
+bool CProgrammableObjectImpl::ReadStack(std::istream &istr)
 {
     short       op;
 
-    CBot::fRead(&op, sizeof(short), 1, file);
+    if (!CBot::ReadShort(istr, op)) return false;
     if ( op == 1 )  // run ?
     {
-        CBot::fRead(&op, sizeof(short), 1, file);  // program rank
+        if (!CBot::ReadShort(istr, op)) return false; // program rank
         if ( op >= 0 )
         {
             if (m_object->Implements(ObjectInterfaceType::ProgramStorage))
             {
-                assert(op < static_cast<int>(dynamic_cast<CProgramStorageObject*>(m_object)->GetProgramCount()));
+                int count = static_cast<int>(dynamic_cast<CProgramStorageObject*>(m_object)->GetProgramCount());
+                if (!(op < count))
+                {
+                    GetLogger()->Info("Object program count: %i\n", count);
+                    GetLogger()->Error("Error in file: program index out of range: %i\n", op);
+                    return false;
+                }
+
                 m_currentProgram = dynamic_cast<CProgramStorageObject*>(m_object)->GetProgram(op);
-                if ( !m_currentProgram->script->ReadStack(file) )  return false;
+                if (!m_currentProgram->script->ReadStack(istr))
+                {
+                    GetLogger()->Error("Restore state failed at program index: %i\n", op);
+                    int errNum = m_currentProgram->script->GetError();
+                    if (errNum != 0)
+                    {
+                        std::string errStr;
+                        m_currentProgram->script->GetError(errStr);
+                        GetLogger()->Error("Program reports error: %i:(%s)\n", errNum, errStr.c_str());
+                    }
+                    return false;
+                }
             }
             else
             {
+                GetLogger()->Error("Object is not a program storage object\n");
                 return false;
             }
         }
@@ -171,7 +190,7 @@ bool CProgrammableObjectImpl::ReadStack(FILE *file)
 
 // Save the script implementation stack of a file.
 
-bool CProgrammableObjectImpl::WriteStack(FILE *file)
+bool CProgrammableObjectImpl::WriteStack(std::ostream &ostr)
 {
     short       op;
 
@@ -179,21 +198,25 @@ bool CProgrammableObjectImpl::WriteStack(FILE *file)
          m_currentProgram->script->IsRunning() )
     {
         op = 1;  // run
-        CBot::fWrite(&op, sizeof(short), 1, file);
+        if (!CBot::WriteShort(ostr, op)) return false;
 
         op = -1;
         if (m_object->Implements(ObjectInterfaceType::ProgramStorage))
         {
             op = dynamic_cast<CProgramStorageObject*>(m_object)->GetProgramIndex(m_currentProgram);
         }
-        CBot::fWrite(&op, sizeof(short), 1, file);
+        if (!CBot::WriteShort(ostr, op)) return false;
 
-        return m_currentProgram->script->WriteStack(file);
+        if (!m_currentProgram->script->WriteStack(ostr))
+        {
+            GetLogger()->Error("Save state failed at program index: %i\n", op);
+            return false;
+        }
+        return true;
     }
 
     op = 0;  // stop
-    CBot::fWrite(&op, sizeof(short), 1, file);
-    return true;
+    return CBot::WriteShort(ostr, op);
 }
 
 
diff --git a/src/object/implementation/programmable_impl.h b/src/object/implementation/programmable_impl.h
index a0b78096..38b8be7c 100644
--- a/src/object/implementation/programmable_impl.h
+++ b/src/object/implementation/programmable_impl.h
@@ -58,8 +58,8 @@ public:
     Program* GetCurrentProgram() override;
     void StopProgram() override;
 
-    bool ReadStack(FILE *file) override;
-    bool WriteStack(FILE *file) override;
+    bool ReadStack(std::istream &istr) override;
+    bool WriteStack(std::ostream &ostr) override;
 
     void TraceRecordStart() override;
     void TraceRecordStop() override;
diff --git a/src/object/interface/programmable_object.h b/src/object/interface/programmable_object.h
index 05f1a92c..1ce0d5d4 100644
--- a/src/object/interface/programmable_object.h
+++ b/src/object/interface/programmable_object.h
@@ -53,9 +53,9 @@ public:
     virtual bool IsProgram() = 0;
 
     //! Save current execution status to file
-    virtual bool WriteStack(FILE *file) = 0;
+    virtual bool WriteStack(std::ostream &ostr) = 0;
     //! Read current execution status from file
-    virtual bool ReadStack(FILE *file) = 0;
+    virtual bool ReadStack(std::istream &istr) = 0;
 
     //! Start recording trace
     virtual void TraceRecordStart() = 0;
diff --git a/src/script/script.cpp b/src/script/script.cpp
index a94e850f..22ae1024 100644
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -1032,16 +1032,16 @@ bool CScript::WriteScript(const char* filename)
 
 // Reads a stack of script by execution as a file.
 
-bool CScript::ReadStack(FILE *file)
+bool CScript::ReadStack(std::istream &istr)
 {
     int     nb;
 
-    CBot::fRead(&nb, sizeof(int), 1, file);
-    CBot::fRead(&m_ipf, sizeof(int), 1, file);
-    CBot::fRead(&m_errMode, sizeof(int), 1, file);
+    if (!CBot::ReadInt(istr, nb)) return false;
+    if (!CBot::ReadInt(istr, m_ipf)) return false;
+    if (!CBot::ReadInt(istr, m_errMode)) return false;
 
     if (m_botProg == nullptr) return false;
-    if ( !m_botProg->RestoreState(file) )  return false;
+    if (!m_botProg->RestoreState(istr)) return false;
 
     m_bRun = true;
     m_bContinue = false;
@@ -1050,16 +1050,16 @@ bool CScript::ReadStack(FILE *file)
 
 // Writes a stack of script by execution as a file.
 
-bool CScript::WriteStack(FILE *file)
+bool CScript::WriteStack(std::ostream &ostr)
 {
     int     nb;
 
     nb = 2;
-    CBot::fWrite(&nb, sizeof(int), 1, file);
-    CBot::fWrite(&m_ipf, sizeof(int), 1, file);
-    CBot::fWrite(&m_errMode, sizeof(int), 1, file);
+    if (!CBot::WriteInt(ostr, nb)) return false;
+    if (!CBot::WriteInt(ostr, m_ipf)) return false;
+    if (!CBot::WriteInt(ostr, m_errMode)) return false;
 
-    return m_botProg->SaveState(file);
+    return m_botProg->SaveState(ostr);
 }
 
 
diff --git a/src/script/script.h b/src/script/script.h
index f0f473fb..bc64dc23 100644
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -88,8 +88,8 @@ public:
     bool        SendScript(const char* text);
     bool        ReadScript(const char* filename);
     bool        WriteScript(const char* filename);
-    bool        ReadStack(FILE *file);
-    bool        WriteStack(FILE *file);
+    bool        ReadStack(std::istream &istr);
+    bool        WriteStack(std::ostream &ostr);
     bool        Compare(CScript* other);
 
     void        SetFilename(const std::string &filename);
diff --git a/test/unit/CBot/CBot_test.cpp b/test/unit/CBot/CBot_test.cpp
index cc3261b8..f16637bd 100644
--- a/test/unit/CBot/CBot_test.cpp
+++ b/test/unit/CBot/CBot_test.cpp
@@ -22,6 +22,9 @@
 #include <gtest/gtest.h>
 #include <stdexcept>
 
+extern bool g_cbotTestSaveState;
+bool g_cbotTestSaveState = false;
+
 using namespace CBot;
 
 class CBotUT : public testing::Test
@@ -197,6 +200,23 @@ private:
         return ss.str();
     }
 
+    static void TestSaveAndRestore(CBotProgram* program)
+    {
+        std::stringstream sstr("");
+        // save
+        if (!program->SaveState(sstr))
+            throw CBotTestFail("CBotProgram::SaveState Failed");
+
+        if (!CBotClass::SaveStaticState(sstr))
+            throw CBotTestFail("CBotClass::SaveStaticState Failed");
+        // restore
+        if (!program->RestoreState(sstr))
+            throw CBotTestFail("CBotProgram::RestoreState Failed");
+
+        if (!CBotClass::RestoreStaticState(sstr))
+            throw CBotTestFail("CBotClass::RestoreStaticState Failed");
+    }
+
 protected:
     std::unique_ptr<CBotProgram> ExecuteTest(const std::string& code, CBotError expectedError = CBotNoErr)
     {
@@ -231,7 +251,17 @@ protected:
             try
             {
                 program->Start(test);
-                while (!program->Run());
+                if (g_cbotTestSaveState)
+                {
+                    while (!program->Run(nullptr, 0)) // save/restore at each step
+                    {
+                        TestSaveAndRestore(program.get());
+                    }
+                }
+                else
+                {
+                    while (!program->Run(nullptr, 0)); // execute in step mode
+                }
                 program->GetError(error, cursor1, cursor2);
                 if (error != expectedRuntimeError)
                 {
diff --git a/test/unit/main.cpp b/test/unit/main.cpp
index 91d640de..8bed282c 100644
--- a/test/unit/main.cpp
+++ b/test/unit/main.cpp
@@ -21,11 +21,21 @@
 
 #include <gtest/gtest.h>
 
+extern bool g_cbotTestSaveState;
+
 int main(int argc, char* argv[])
 {
     CLogger logger;
 
     ::testing::InitGoogleTest(&argc, argv);
 
+    // parse arguments not removed by InitGoogleTest
+    for (int i = 1; i < argc; ++i)
+    {
+        std::string arg(argv[i]);
+        if (arg == "--CBotUT_TestSaveState")
+            g_cbotTestSaveState = true;
+    }
+
     return RUN_ALL_TESTS();
 }