diff --git a/js/ui/shellDBus.js b/js/ui/shellDBus.js
index 48e7bb5b8..6574cc528 100644
--- a/js/ui/shellDBus.js
+++ b/js/ui/shellDBus.js
@@ -217,11 +217,13 @@ var GnomeShell = class {
         let sender = invocation.get_sender();
         let [dict] = params;
         Main.osdMonitorLabeler.show(sender, dict);
+        invocation.return_value(null);
     }
 
     HideMonitorLabelsAsync(params, invocation) {
         let sender = invocation.get_sender();
         Main.osdMonitorLabeler.hide(sender);
+        invocation.return_value(null);
     }
 
     _checkOverviewVisibleChanged() {