diff --git a/kiss b/kiss
index d0f6613..9274ff6 100755
--- a/kiss
+++ b/kiss
@@ -1247,9 +1247,8 @@ file_rwx() {
         rwx=${rwx#?}
 
         case $rwx in
-            [rwx]*): "$((o+=${c#?}))" ;;
-             [st]*): "$((o+=1))" ;;
-             [ST]*) ;;
+            [rwx]*) o=$((o + ${c#?})) ;;
+             [st]*) o=$((o + 1)) ;;
         esac
 
         case $((${c%?} % 3)) in 0)