diff -up openbox-3.6.1/data/xsession/openbox-kde-session.in.kf5menu openbox-3.6.1/data/xsession/openbox-kde-session.in
--- openbox-3.6.1/data/xsession/openbox-kde-session.in.kf5menu	2011-10-16 18:13:18.000000000 +0200
+++ openbox-3.6.1/data/xsession/openbox-kde-session.in	2020-11-09 10:42:43.755217411 +0100
@@ -8,7 +8,7 @@ if test -n "$1"; then
 fi
 
 # Set the prefix for the menu layout to use
-export XDG_MENU_PREFIX="kde-4-"
+export XDG_MENU_PREFIX="kf5-"
 
 # Clean up after GDM
 xprop -root -remove _NET_NUMBER_OF_DESKTOPS \