diff --git a/lock-screen b/lock-screen
index 06334ed..303bec5 100755
--- a/lock-screen
+++ b/lock-screen
@@ -2,7 +2,7 @@
 BACKGROUND='/tmp/screen_locked.png'
 notify-send DUNST_COMMAND_PAUSE
 scrot $BACKGROUND
-mogrify -scale 10% -scale 1000% $BACKGROUND
+mogrify -scale 10% -colorspace GRAY -scale 1000% $BACKGROUND
 until i3lock -entc 661111 -i $BACKGROUND; do :; done
 rm $BACKGROUND
 notify-send DUNST_COMMAND_RESUME