diff --git a/bin/sekrit.sh b/bin/sekrit.sh
index 9a2f192..1a144bc 100644
--- a/bin/sekrit.sh
+++ b/bin/sekrit.sh
@@ -48,7 +48,11 @@ err()
 
 check_key()
 {
-	[ "$1" = "${1%/}" ] || err "Key can not end in a slash."
+	case $1 in
+	*/ | /* | ./* | */./* | */. | ../* | */../* | */..)
+		err "Key can not end in a slash."
+		;;
+	esac
 }
 
 to_number()