diff --git a/dom/base/nsMimeTypeArray.h b/dom/base/nsMimeTypeArray.h
index dfaedb7585d8..e039da026ac4 100644
--- a/dom/base/nsMimeTypeArray.h
+++ b/dom/base/nsMimeTypeArray.h
@@ -102,6 +102,8 @@ public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIDOMMIMETYPE
 
+  void DetachPlugin() { mPlugin = nsnull; }
+
 protected:
   nsIDOMPlugin* mPlugin;
   nsCOMPtr<nsIDOMMimeType> mMimeType;
diff --git a/dom/base/nsPluginArray.cpp b/dom/base/nsPluginArray.cpp
index c14c6b6b0bb7..7c2e597980cf 100644
--- a/dom/base/nsPluginArray.cpp
+++ b/dom/base/nsPluginArray.cpp
@@ -285,8 +285,13 @@ nsPluginElement::~nsPluginElement()
   NS_IF_RELEASE(mPlugin);
 
   if (mMimeTypeArray != nsnull) {
-    for (PRUint32 i = 0; i < mMimeTypeCount; i++)
-      NS_IF_RELEASE(mMimeTypeArray[i]);
+    for (PRUint32 i = 0; i < mMimeTypeCount; i++) {
+      nsMimeType* mt = static_cast<nsMimeType*>(mMimeTypeArray[i]);
+      if (mt) {
+        mt->DetachPlugin();
+        NS_RELEASE(mt);
+      }
+    }
     delete[] mMimeTypeArray;
   }
 }