diff --git a/TimeMachineStatus/AppDelegate.swift b/TimeMachineStatus/AppDelegate.swift
index 6aa955f..636f3ad 100644
--- a/TimeMachineStatus/AppDelegate.swift
+++ b/TimeMachineStatus/AppDelegate.swift
@@ -156,6 +156,7 @@ class DetachedWindowController: NSWindowController {
         window.standardWindowButton(.zoomButton)?.isHidden = true
     }
 
+    @available(*, unavailable)
     required init?(coder: NSCoder) {
         fatalError("init(coder:) has not been implemented")
     }