diff --git a/src/gui/lua/luainstance_helpers.cpp b/src/gui/lua/luainstance_helpers.cpp
index 88277fdd7..0be6b3a50 100644
--- a/src/gui/lua/luainstance_helpers.cpp
+++ b/src/gui/lua/luainstance_helpers.cpp
@@ -84,7 +84,7 @@ void functionDeprecated(lua_State *L, const char* oldFunc, const char* newFunc)
 					ar.short_src, ar.currentline);
 }
 
-lua_Unsigned checkMagicMask(lua_Unsigned &col)
+lua_Unsigned checkMagicMask(lua_Unsigned col)
 {
 	if ((col & MAGIC_MASK) == MAGIC_COLOR)
 		col = CFrameBuffer::getInstance()->realcolor[col & 0x000000ff];
diff --git a/src/gui/lua/luainstance_helpers.h b/src/gui/lua/luainstance_helpers.h
index 99eaa8cce..6c636fd1d 100644
--- a/src/gui/lua/luainstance_helpers.h
+++ b/src/gui/lua/luainstance_helpers.h
@@ -85,7 +85,7 @@ bool _luaL_checkbool(lua_State *L, int numArg);
 void paramBoolDeprecated(lua_State *L, const char* val);
 void paramDeprecated(lua_State *L, const char* oldParam, const char* newParam);
 void functionDeprecated(lua_State *L, const char* oldFunc, const char* newFunc);
-lua_Unsigned checkMagicMask(lua_Unsigned &col);
+lua_Unsigned checkMagicMask(lua_Unsigned col);
 
 bool tableLookup(lua_State*, const char*, std::string&);
 bool tableLookup(lua_State*, const char*, lua_Integer&);