The initial Surfer instance was sometimes free'd twice

src/callbacks.c

@@ -41,10 +41,9 @@ gboolean on_closex(GtkWidget * widget, GdkEvent * event, gpointer data)
 {
 	Surfer * surfer = data;
 
-	if(surfer_cnt == 1)
+	surfer_delete(surfer);
+	if(surfer_cnt == 0)
 		gtk_main_quit();
-	else
-		surfer_delete(surfer);
 	return FALSE;
 }
 

src/main.c

@@ -54,6 +54,5 @@ int main(int argc, char * argv[])
 	if(surfer == NULL)
 		return 2;
 	gtk_main();
-	surfer_delete(surfer);
 	return 0;
 }