diff --git a/sw/ground_segment/tmtc/messages.ml b/sw/ground_segment/tmtc/messages.ml
index e12253a037..1edbb07ca3 100644
--- a/sw/ground_segment/tmtc/messages.ml
+++ b/sw/ground_segment/tmtc/messages.ml
@@ -199,7 +199,7 @@ let _ =
 
   (** Open the window container with its notebook*)
   let icon = GdkPixbuf.from_file Env.icon_file in
-  let window = GWindow.window ~icon ~title:"Messages" () in
+  let window = GWindow.window ~type_hint:`DIALOG ~icon ~title:"Messages" () in
   let quit = fun () -> GMain.Main.quit (); exit 0 in
   ignore (window#connect#destroy ~callback:quit);
 
diff --git a/sw/simulator/sim.ml b/sw/simulator/sim.ml
index aa131685ea..6d858b01df 100644
--- a/sw/simulator/sim.ml
+++ b/sw/simulator/sim.ml
@@ -121,7 +121,7 @@ module Make(AircraftItl : AIRCRAFT_ITL) = struct
 
   let main () =
     let icon = GdkPixbuf.from_file Env.icon_file in
-    let window = GWindow.window ~icon ~title: !ac_name () in
+    let window = GWindow.window ~type_hint:`DIALOG ~icon ~title: !ac_name () in
     let quit = fun () -> GMain.Main.quit (); exit 0 in
     ignore (window#connect#destroy ~callback:quit);
     let vbox = GPack.vbox ~packing:window#add () in