diff --git a/src/plugins/platforms/cocoa/qcocoamenu.mm b/src/plugins/platforms/cocoa/qcocoamenu.mm
index e5681c0894..d7f0efe86c 100644
--- a/src/plugins/platforms/cocoa/qcocoamenu.mm
+++ b/src/plugins/platforms/cocoa/qcocoamenu.mm
@@ -328,6 +328,13 @@ void QCocoaMenu::insertMenuItem(QPlatformMenuItem *menuItem, QPlatformMenuItem *
     }
 
     insertNative(cocoaItem, beforeItem);
+
+    // Empty menus on a menubar are hidden by default. If the menu gets
+    // added to the menubar before it contains any item, we need to sync.
+    if (isVisible() && attachedItem().hidden) {
+        if (auto *mb = qobject_cast<QCocoaMenuBar *>(menuParent()))
+            mb->syncMenu(this);
+    }
 }
 
 void QCocoaMenu::insertNative(QCocoaMenuItem *item, QCocoaMenuItem *beforeItem)
diff --git a/src/plugins/platforms/cocoa/qcocoamenubar.mm b/src/plugins/platforms/cocoa/qcocoamenubar.mm
index 4cdf004dd1..70fcb40774 100644
--- a/src/plugins/platforms/cocoa/qcocoamenubar.mm
+++ b/src/plugins/platforms/cocoa/qcocoamenubar.mm
@@ -370,7 +370,7 @@ void QCocoaMenuBar::updateMenuBarImmediately()
     QCocoaMenuLoader *loader = [QCocoaMenuLoader sharedMenuLoader];
     [loader ensureAppMenuInMenu:mb->nsMenu()];
 
-    NSMutableSet *mergedItems = [[NSMutableSet setWithCapacity:0] retain];
+    NSMutableSet *mergedItems = [[NSMutableSet setWithCapacity:mb->merged().count()] retain];
     foreach (QCocoaMenuItem *m, mb->merged()) {
         [mergedItems addObject:m->nsItem()];
         m->syncMerged();