diff --git a/gui/listbox.cpp b/gui/listbox.cpp
index 99e2ded..bbfc934 100644
--- a/gui/listbox.cpp
+++ b/gui/listbox.cpp
@@ -760,8 +760,10 @@
 	return 0;
 }
 
-int GUIListBox::NotifyVarChange(std::string varName, std::string value)
+int GUIListBox::NotifyVarChange(const std::string& varName, const std::string& value)
 {
+	GUIObject::NotifyVarChange(varName, value);
+
 	if(!isConditionTrue())
 		return 0;