diff -r 832e9288f8e2 -r 6691e007cef7 ui/gtk/toolkit.h
--- a/ui/gtk/toolkit.h	Wed Dec 31 11:36:42 2025 +0100
+++ b/ui/gtk/toolkit.h	Wed Dec 31 12:37:09 2025 +0100
@@ -190,7 +190,7 @@
 void ui_set_widget_nvisibility_states(UiContext *ctx, GtkWidget *widget, const int *states, size_t ngroups);
 
 void ui_destroy_userdata(GtkWidget *object, void *userdata);
-void ui_destroy_vardata(GtkWidget *object, UiVarEventData *data);
+void ui_destroy_vardata(GtkWidget *unused, UiVarEventData *data);
 void ui_destroy_widget_var(GtkWidget *object, UiVar *var);
 void ui_destroy_boundvar(UiContext *ctx, UiVar *var);