diff --git a/src/CBot/CBotClass.h b/src/CBot/CBotClass.h
index 10bb83ca..68b61cc6 100644
--- a/src/CBot/CBotClass.h
+++ b/src/CBot/CBotClass.h
@@ -275,10 +275,15 @@ public:
                               CBotCStack* pStack);
 
     /*!
-     * \brief Compile1
-     * \param p
-     * \param pStack
-     * \return
+     * \brief Pre-compile a new class
+     * \param p[in, out] Pointer to first token of the class, will be updated to point to first token after the class definition
+     * \param pStack Compile stack
+     *
+     * This function is used to find the beginning and end of class definition.
+     *
+     * If any errors in the code are detected, this function will set the error on compile stack and return nullptr.
+     *
+     * \return Precompiled class, or nullptr in case of error
      */
     static CBotClass* Compile1(CBotToken* &p,
                                CBotCStack* pStack);
diff --git a/src/CBot/CBotInstr/CBotFunction.h b/src/CBot/CBotInstr/CBotFunction.h
index 66637b51..bab5e2bb 100644
--- a/src/CBot/CBotInstr/CBotFunction.h
+++ b/src/CBot/CBotInstr/CBotFunction.h
@@ -60,11 +60,16 @@ public:
                                  bool bLocal = true);
 
     /*!
-     * \brief Compile1 Pre-compile a new function.
-     * \param p
-     * \param pStack
-     * \param pClass
-     * \return
+     * \brief Pre-compile a new function
+     * \param p[in, out] Pointer to first token of the function, will be updated to point to first token after the function definition
+     * \param pStack Compile stack
+     * \param pClass If this is a class method, pointer to class this function is part of, otherwise nullptr
+     *
+     * This function is used to find the beginning and end of function definition.
+     *
+     * If any errors in the code are detected, this function will set the error on compile stack and return nullptr.
+     *
+     * \return Precompiled function, or nullptr in case of error
      */
     static CBotFunction* Compile1(CBotToken* &p,
                                   CBotCStack* pStack,
diff --git a/src/CBot/CBotProgram.cpp b/src/CBot/CBotProgram.cpp
index fdb36eb8..dce62198 100644
--- a/src/CBot/CBotProgram.cpp
+++ b/src/CBot/CBotProgram.cpp
@@ -93,11 +93,15 @@ bool CBotProgram::Compile(const std::string& program, std::vector<std::string>&
         if ( p->GetType() == ID_CLASS ||
             ( p->GetType() == ID_PUBLIC && p->GetNext()->GetType() == ID_CLASS ))
         {
-            m_classes.push_back(CBotClass::Compile1(p, pStack.get()));
+            CBotClass* newclass = CBotClass::Compile1(p, pStack.get());
+            if (newclass != nullptr)
+                m_classes.push_back(newclass);
         }
         else
         {
-            m_functions.push_back(CBotFunction::Compile1(p, pStack.get(), nullptr));
+            CBotFunction* newfunc  = CBotFunction::Compile1(p, pStack.get(), nullptr);
+            if (newfunc != nullptr)
+                m_functions.push_back(newfunc);
         }
     }