diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index 046934277c..5ff77092ab 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -2817,10 +2817,10 @@ bool
 ContentChild::RecvGetFilesResponse(const nsID& aUUID,
                                    const GetFilesResponseResult& aResult)
 {
-  GetFilesHelperChild* child = mGetFilesPendingRequests.GetWeak(aUUID);
+  RefPtr<GetFilesHelperChild> child;
   // This object can already been deleted in case DeleteGetFilesRequest has
   // been called when the response was sending by the parent.
-  if (!child) {
+  if (!mGetFilesPendingRequests.Remove(aUUID, getter_AddRefs(child))) {
     return true;
   }
 
@@ -2841,7 +2841,6 @@ ContentChild::RecvGetFilesResponse(const nsID& aUUID,
     child->Finished(succeeded ? NS_OK : NS_ERROR_OUT_OF_MEMORY);
   }
 
-  mGetFilesPendingRequests.Remove(aUUID);
   return true;
 }
 
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 2dd771de03..53947f3c96 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1353,6 +1353,7 @@ pref("network.protocol-handler.external.iehistory", false);
 pref("network.protocol-handler.external.ierss", false);
 pref("network.protocol-handler.external.mk", false);
 pref("network.protocol-handler.external.ms-help", false);
+pref("network.protocol-handler.external.mk", false);
 pref("network.protocol-handler.external.res", false);
 pref("network.protocol-handler.external.shell", false);
 pref("network.protocol-handler.external.vnd.ms.radio", false);