diff --git a/expression.c b/expression.c
index 6f4f701..9cef20f 100644
--- a/expression.c
+++ b/expression.c
@@ -1134,7 +1134,7 @@ void ExpressionParseFunctionCall(struct ParseState *Parser, struct ExpressionSta
             TopStackFrame->NumParams = ArgCount;
             TopStackFrame->ReturnValue = ReturnValue;
             for (Count = 0; Count < FuncValue->Val->FuncDef.NumParams; Count++)
-                VariableDefine(Parser, FuncValue->Val->FuncDef.ParamName[Count], ParamArray[Count]);
+                VariableDefine(Parser, FuncValue->Val->FuncDef.ParamName[Count], ParamArray[Count], TRUE);
                 
             if (!ParseStatement(&FuncParser))
                 ProgramFail(&FuncParser, "function body expected");
diff --git a/parse.c b/parse.c
index 6a80744..3ecfae8 100644
--- a/parse.c
+++ b/parse.c
@@ -127,14 +127,14 @@ int ParseDeclaration(struct ParseState *Parser, enum LexToken Token)
                     ProgramFail(Parser, "can't define a void variable");
                     
                 if (LexGetToken(Parser, NULL, FALSE) != TokenAssign)
-                    VariableDefine(Parser, Identifier, VariableAllocValueFromType(Parser, Typ, TRUE, NULL));
+                    VariableDefine(Parser, Identifier, VariableAllocValueFromType(Parser, Typ, TRUE, NULL), TRUE);
                 else
                 { /* we're assigning an initial value */
                     LexGetToken(Parser, NULL, TRUE);
                     if (!ExpressionParse(Parser, &CValue))
                         ProgramFail(Parser, "expression expected");
                         
-                    VariableDefine(Parser, Identifier, CValue);
+                    VariableDefine(Parser, Identifier, CValue, TRUE);
                     if (Parser->Mode == RunModeRun)
                         VariableStackPop(Parser, CValue);
                 }
diff --git a/picoc.h b/picoc.h
index 8c3b359..741f15d 100644
--- a/picoc.h
+++ b/picoc.h
@@ -350,7 +350,7 @@ struct Value *VariableAllocValueAndCopy(struct ParseState *Parser, struct Value
 struct Value *VariableAllocValueFromType(struct ParseState *Parser, struct ValueType *Typ, int IsLValue, struct Value *LValueFrom);
 struct Value *VariableAllocValueFromExistingData(struct ParseState *Parser, struct ValueType *Typ, union AnyValue *FromValue, int IsLValue, struct Value *LValueFrom);
 struct Value *VariableAllocValueShared(struct ParseState *Parser, struct Value *FromValue);
-void VariableDefine(struct ParseState *Parser, char *Ident, struct Value *InitValue);
+void VariableDefine(struct ParseState *Parser, char *Ident, struct Value *InitValue, int MakeWritable);
 int VariableDefined(const char *Ident);
 void VariableGet(struct ParseState *Parser, const char *Ident, struct Value **LVal);
 void VariableDefinePlatformVar(struct ParseState *Parser, char *Ident, struct ValueType *Typ, union AnyValue *FromValue, int IsWritable);
diff --git a/type.c b/type.c
index ded7b93..c882317 100644
--- a/type.c
+++ b/type.c
@@ -270,7 +270,7 @@ void TypeParseEnum(struct ParseState *Parser, struct ValueType **Typ)
             EnumValue = ExpressionParseInt(Parser);
         }
         
-        VariableDefine(Parser, EnumIdentifier, &InitValue);
+        VariableDefine(Parser, EnumIdentifier, &InitValue, FALSE);
             
         Token = LexGetToken(Parser, NULL, TRUE);
         if (Token != TokenComma && Token != TokenRightBrace)
diff --git a/variable.c b/variable.c
index ff5f9a8..e47ca97 100644
--- a/variable.c
+++ b/variable.c
@@ -145,9 +145,14 @@ struct Value *VariableAllocValueShared(struct ParseState *Parser, struct Value *
 }
 
 /* define a variable. Ident must be registered */
-void VariableDefine(struct ParseState *Parser, char *Ident, struct Value *InitValue)
+void VariableDefine(struct ParseState *Parser, char *Ident, struct Value *InitValue, int MakeWritable)
 {
-    if (!TableSet((TopStackFrame == NULL) ? &GlobalTable : &TopStackFrame->LocalTable, Ident, VariableAllocValueAndCopy(Parser, InitValue, TopStackFrame == NULL)))
+    struct Value *AssignValue = VariableAllocValueAndCopy(Parser, InitValue, TopStackFrame == NULL);
+    
+    if (MakeWritable)
+        AssignValue->IsLValue = TRUE;
+        
+    if (!TableSet((TopStackFrame == NULL) ? &GlobalTable : &TopStackFrame->LocalTable, Ident, AssignValue))
         ProgramFail(Parser, "'%s' is already defined", Ident);
 }