--- a/netwerk/dns/nsDNSService2.cpp
+++ b/netwerk/dns/nsDNSService2.cpp
@@ -250,30 +250,30 @@ public:
 
     nsDNSAsyncRequest(nsHostResolver   *res,
                       const nsACString &host,
                       nsIDNSListener   *listener,
                       uint16_t          flags,
                       uint16_t          af)
         : mResolver(res)
         , mHost(host)
-        , mListener(new nsMainThreadPtrHolder<nsIDNSListener>(listener))
+        , mListener(listener)
         , mFlags(flags)
         , mAF(af) {}
     ~nsDNSAsyncRequest() {}
 
     void OnLookupComplete(nsHostResolver *, nsHostRecord *, nsresult);
     // Returns TRUE if the DNS listener arg is the same as the member listener
     // Used in Cancellations to remove DNS requests associated with a
     // particular hostname and nsIDNSListener
     bool EqualsAsyncListener(nsIDNSListener *aListener);
 
     nsRefPtr<nsHostResolver> mResolver;
     nsCString                mHost; // hostname we're resolving
-    nsMainThreadPtrHandle<nsIDNSListener> mListener;
+    nsCOMPtr<nsIDNSListener> mListener;
     uint16_t                 mFlags;
     uint16_t                 mAF;
 };
 
 void
 nsDNSAsyncRequest::OnLookupComplete(nsHostResolver *resolver,
                                     nsHostRecord   *hostRecord,
                                     nsresult        status)
@@ -287,16 +287,17 @@ nsDNSAsyncRequest::OnLookupComplete(nsHo
         rec = new nsDNSRecord(hostRecord);
         if (!rec)
             status = NS_ERROR_OUT_OF_MEMORY;
     }
 
     MOZ_EVENT_TRACER_DONE(this, "net::dns::lookup");
 
     mListener->OnLookupComplete(this, rec, status);
+    mListener = nullptr;
 
     // release the reference to ourselves that was added before we were
     // handed off to the host resolver.
     NS_RELEASE_THIS();
 }
 
 bool
 nsDNSAsyncRequest::EqualsAsyncListener(nsIDNSListener *aListener)