diff --git a/scripts/lock b/scripts/lock
index bec03ab..f1ee2f4 100755
--- a/scripts/lock
+++ b/scripts/lock
@@ -2,9 +2,9 @@
 icon=$HOME/img/misc/lock.png
 tmpbg=/tmp/screenshot.png
 
-(( $# )) && { icon=$1; }
+test $# -eq 1 && icon=$1
 
 scrot $tmpbg
 gm convert $tmpbg -scale 10% -scale 1000% $tmpbg
-gm composite -resize 256x256^ -gravity center $icon $tmpbg $tmpbg
+gm composite -resize 256x256^ -gravity center "$icon" $tmpbg $tmpbg
 i3lock -e -u -i $tmpbg 2>/dev/null