diff --git a/mozilla/layout/generic/nsObjectFrame.cpp b/mozilla/layout/generic/nsObjectFrame.cpp
index 6452d1a4861..6189e3e014b 100644
--- a/mozilla/layout/generic/nsObjectFrame.cpp
+++ b/mozilla/layout/generic/nsObjectFrame.cpp
@@ -864,6 +864,8 @@ nsObjectFrame::InstantiatePlugin(nsIPluginHost* aPluginHost,
                                                 mInstanceOwner);
   }
 
+  // Note that |this| may very well be destroyed already!
+
   if (appShell) {
     appShell->ResumeNative();
   }
@@ -1589,7 +1591,8 @@ nsObjectFrame::HandleEvent(nsPresContext* aPresContext,
   return rv;
 }
 
-nsresult nsObjectFrame::GetPluginInstance(nsIPluginInstance*& aPluginInstance)
+nsresult
+nsObjectFrame::GetPluginInstance(nsIPluginInstance*& aPluginInstance)
 {
   aPluginInstance = nsnull;
 
@@ -1646,9 +1649,16 @@ nsObjectFrame::Instantiate(nsIChannel* aChannel, nsIStreamListener** aStreamList
   // This must be done before instantiating the plugin
   FixupWindow(mRect.Size());
 
+  nsWeakFrame weakFrame(this);
+
   NS_ASSERTION(!mPreventInstantiation, "Say what?");
   mPreventInstantiation = PR_TRUE;
   rv = pluginHost->InstantiatePluginForChannel(aChannel, mInstanceOwner, aStreamListener);
+
+  if (!weakFrame.IsAlive()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
   NS_ASSERTION(mPreventInstantiation,
                "Instantiation should still be prevented!");
   mPreventInstantiation = PR_FALSE;
@@ -1674,6 +1684,8 @@ nsObjectFrame::Instantiate(const char* aMimeType, nsIURI* aURI)
   nsresult rv = PrepareInstanceOwner();
   NS_ENSURE_SUCCESS(rv, rv);
 
+  nsWeakFrame weakFrame(this);
+
   // This must be done before instantiating the plugin
   FixupWindow(mRect.Size());
 
@@ -1687,9 +1699,18 @@ nsObjectFrame::Instantiate(const char* aMimeType, nsIURI* aURI)
 
   rv = InstantiatePlugin(pluginHost, aMimeType, aURI);
 
+  if (!weakFrame.IsAlive()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
   // finish up
   if (NS_SUCCEEDED(rv)) {
     TryNotifyContentObjectWrapper();
+
+    if (!weakFrame.IsAlive()) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+
     CallSetWindow();
   }