diff --git a/src/common/stringutils.cpp b/src/common/stringutils.cpp
index b8639df3..fd8387f5 100644
--- a/src/common/stringutils.cpp
+++ b/src/common/stringutils.cpp
@@ -173,14 +173,19 @@ int StrUtils::Utf8CharSizeAt(const std::string &str, unsigned int pos)
     if (pos >= str.size())
         return 0;
 
-    if ((str[pos] & 0x80) == 0)
-        return 1;
-    else if ((str[pos] & 0xC0) == 0xC0)
-        return 2;
-    else
+    const char c = str[pos];
+    if(c >= 0xF0)
+        return 4;
+    if(c >= 0xE0)
         return 3;
+    if(c >= 0xC0)
+        return 2;
 
-    return 0;
+    // Invalid char - unexpected continuation byte
+    if(c >= 0x80)
+        return 0;
+    
+    return 1;
 }
 
 std::size_t StrUtils::Utf8StringLength(const std::string &str)