diff --git a/contrib/service b/contrib/service
index 9ebd117..6efd7c1 100644
--- a/contrib/service
+++ b/contrib/service
@@ -32,9 +32,11 @@ _service()
     return 0
 } &&
 complete -F _service service
-[ -d /etc/init.d/ ] && complete -F _service -o default \
-    $(for i in /etc/init.d/*; do
-    complete -p ${i##*/} &>/dev/null || printf '%s\n' ${i##*/}; done)
+for svc in /etc/init.d/*; do
+    [ ! -x "$svc" ] || complete -p "${svc##*/}" &>/dev/null || \
+        complete -F _service -o default "${svc##*/}"
+done
+unset svc
 
 # Local variables:
 # mode: shell-script