diff --git a/src/gui_beval.c b/src/gui_beval.c
index ba8e32e..68b85ee 100644
--- a/src/gui_beval.c
+++ b/src/gui_beval.c
@@ -1011,6 +1011,7 @@
 createBalloonEvalWindow(BalloonEval *beval)
 {
     beval->balloonShell = gtk_window_new(GTK_WINDOW_POPUP);
+    gtk_window_set_transient_for(GTK_WINDOW(beval->balloonShell), GTK_WINDOW(gui.mainwin));
 
     gtk_widget_set_app_paintable(beval->balloonShell, TRUE);
     gtk_window_set_resizable(GTK_WINDOW(beval->balloonShell), FALSE);