diff --git a/layout/xul/nsMenuBarFrame.cpp b/layout/xul/nsMenuBarFrame.cpp
index 324c5014ee39..80aa98fbd7fd 100644
--- a/layout/xul/nsMenuBarFrame.cpp
+++ b/layout/xul/nsMenuBarFrame.cpp
@@ -85,6 +85,8 @@ nsMenuBarFrame::Init(nsIContent*       aContent,
   mTarget->AddEventListener(NS_LITERAL_STRING("mousedown"), mMenuBarListener, true);
   mTarget->AddEventListener(NS_LITERAL_STRING("mousedown"), mMenuBarListener, false);
   mTarget->AddEventListener(NS_LITERAL_STRING("blur"), mMenuBarListener, true);
+
+  mTarget->AddEventListener(NS_LITERAL_STRING("MozDOMFullscreen:Entered"), mMenuBarListener, false);
 }
 
 NS_IMETHODIMP
@@ -423,6 +425,8 @@ nsMenuBarFrame::DestroyFrom(nsIFrame* aDestructRoot)
   mTarget->RemoveEventListener(NS_LITERAL_STRING("mousedown"), mMenuBarListener, false);
   mTarget->RemoveEventListener(NS_LITERAL_STRING("blur"), mMenuBarListener, true);
 
+  mTarget->RemoveEventListener(NS_LITERAL_STRING("MozDOMFullscreen:Entered"), mMenuBarListener, false);
+
   mMenuBarListener->OnDestroyMenuBarFrame();
   mMenuBarListener = nullptr;
 
diff --git a/layout/xul/nsMenuBarListener.cpp b/layout/xul/nsMenuBarListener.cpp
index c0a8bb9fbeef..35a33ba0661f 100644
--- a/layout/xul/nsMenuBarListener.cpp
+++ b/layout/xul/nsMenuBarListener.cpp
@@ -403,6 +403,17 @@ nsMenuBarListener::MouseDown(nsIDOMEvent* aMouseEvent)
   return NS_OK; // means I am NOT consuming event
 }
 
+////////////////////////////////////////////////////////////////////////
+
+nsresult
+nsMenuBarListener::Fullscreen(nsIDOMEvent* aEvent)
+{
+  if (mMenuBarFrame->IsActive()) {
+    ToggleMenuActiveState();
+  }
+  return NS_OK;
+}
+
 ////////////////////////////////////////////////////////////////////////
 nsresult
 nsMenuBarListener::HandleEvent(nsIDOMEvent* aEvent)
@@ -433,6 +444,9 @@ nsMenuBarListener::HandleEvent(nsIDOMEvent* aEvent)
   if (eventType.EqualsLiteral("mousedown")) {
     return MouseDown(aEvent);
   }
+  if (eventType.EqualsLiteral("MozDOMFullscreen:Entered")) {
+    return Fullscreen(aEvent);
+  }
 
   NS_ABORT();
 
diff --git a/layout/xul/nsMenuBarListener.h b/layout/xul/nsMenuBarListener.h
index c4b2673b2948..3656c89e21d7 100644
--- a/layout/xul/nsMenuBarListener.h
+++ b/layout/xul/nsMenuBarListener.h
@@ -35,6 +35,7 @@ public:
   nsresult KeyPress(nsIDOMEvent* aMouseEvent);
   nsresult Blur(nsIDOMEvent* aEvent);
   nsresult MouseDown(nsIDOMEvent* aMouseEvent);
+  nsresult Fullscreen(nsIDOMEvent* aEvent);
 
   static nsresult GetMenuAccessKey(int32_t* aAccessKey);