diff --git a/appvm-scripts/usr/lib/qubes/qubes-gui-agent-pre.sh.orig b/appvm-scripts/usr/lib/qubes/qubes-gui-agent-pre.sh
index 76e0227..268cb00 100755
--- a/appvm-scripts/usr/lib/qubes/qubes-gui-agent-pre.sh.orig
+++ b/appvm-scripts/usr/lib/qubes/qubes-gui-agent-pre.sh
@@ -25,7 +25,7 @@ if [ -n "$debug_mode" ] && [ "$debug_mode" -gt 0 ]; then
     gui_opts="$gui_opts -vv"
 fi
 
-echo "GUI_OPTS=$gui_opts" >> /var/run/qubes-service-environment
+echo "GUI_OPTS=\"$gui_opts\"" >> /var/run/qubes-service-environment
 
 # 2**30
 echo 1073741824 > /sys/module/xen_gntalloc/parameters/limit