diff --git a/xdg-config-dir/herbstluftwm/autostart b/xdg-config-dir/herbstluftwm/autostart
index e680f8d..d9fb668 100755
--- a/xdg-config-dir/herbstluftwm/autostart
+++ b/xdg-config-dir/herbstluftwm/autostart
@@ -154,7 +154,7 @@ hc rule windowtype~"_NET_WM_WINDOW_TYPE_(NOTIFICATION|DOCK|DESKTOP)" manage=off
 
 hc rule class=XTerm pseudotile=on
 hc rule class~"[Ff]irefox.*" pseudotile=on tag=3
-hc rule class~"[Ff]irefox.*" instance=Navigator pseudotile=on tag=3
+hc rule class~"[Ff]irefox.*" instance=Navigator fullscreen=on tag=3
 hc rule class="Tor Browser" pseudotile=on tag=3
 hc rule class="Tor Browser" instance=Navigator fullscreen=on tag=3
 hc rule class=SshAskpass pseudotile=on