diff --git a/Sources/AppBundle/GlobalObserver.swift b/Sources/AppBundle/GlobalObserver.swift
index c19a896e..e94f795f 100644
--- a/Sources/AppBundle/GlobalObserver.swift
+++ b/Sources/AppBundle/GlobalObserver.swift
@@ -2,6 +2,10 @@ import AppKit
 
 class GlobalObserver {
     private static func onNotif(_ notification: Notification) {
+        // Second line of defence against lock screen window. See: gcWindows
+        if (notification.userInfo?[NSWorkspace.applicationUserInfoKey] as? NSRunningApplication)?.bundleIdentifier == lockScreenAppBundleId {
+            return
+        }
         refreshAndLayout()
     }