--- treesize-0.54.1.old/src/callbacks.c
+++ treesize-0.54.1/src/callbacks.c
@@ -109,7 +109,8 @@
 	gtk_widget_show(file_selector);
 }
 
-GdkPixbuf* gdkTreeSize;
+extern GdkPixbuf* gdkTreeSize;
+
 void on_btnAbout_clicked(GtkToolButton *toolbutton, gpointer user_data) {
 	GtkWidget *aboutDialog = create_AboutDialog();
 	gtk_window_set_modal(GTK_WINDOW(aboutDialog), TRUE);