diff --git a/gifgen b/gifgen
index 4cba179..400c995 100755
--- a/gifgen
+++ b/gifgen
@@ -47,8 +47,7 @@ while getopts "hi:o:f:sv" opt; do
       ;;
   esac
 done
-shift $(($OPTIND - 1))
-
+shift "$((OPTIND-1))"
 # Grab input file from end of command
 input=$1