diff --git a/libs/systemd.js b/libs/systemd.js
index 9254096..34647b6 100644
--- a/libs/systemd.js
+++ b/libs/systemd.js
@@ -18,7 +18,9 @@ async function setServiceState(name, args) {
     }
     let state = args.get('state');
     if (state === undefined) {
-        return;
+        const msg = 'missing argument \'state\', pass either \'active\', \'inactive\' or \'toggle\'';
+        logger.debug(msg);
+        return { err: msg };
     }
     if (state !== constants.SYSTEMD_STATE_ACTIVE && state !== constants.SYSTEMD_STATE_INACTIVE && state !== constants.SYSTEMD_STATE_TOGGLE) {
         const msg = 'can not set state of service \'' + name + '\' to unknown state \'' + state + '\'';