--- a/dom/archivereader/ArchiveZipFile.cpp
+++ b/dom/archivereader/ArchiveZipFile.cpp
@@ -397,17 +397,17 @@ ArchiveZipFileImpl::Traverse(nsCycleColl
   ArchiveZipFileImpl* tmp = this;
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mArchiveReader);
 }
 
 already_AddRefed<mozilla::dom::FileImpl>
 ArchiveZipFileImpl::CreateSlice(uint64_t aStart,
                                 uint64_t aLength,
                                 const nsAString& aContentType,
-                                ErrorResult& aRv)
+                                mozilla::ErrorResult& aRv)
 {
   nsRefPtr<FileImpl> impl =
     new ArchiveZipFileImpl(mFilename, mContentType, aStart, mLength, mCentral,
                            mArchiveReader);
   return impl.forget();
 }
 
 NS_IMPL_ISUPPORTS_INHERITED0(ArchiveZipFileImpl, FileImpl)

--- a/dom/archivereader/ArchiveZipFile.h
+++ b/dom/archivereader/ArchiveZipFile.h
@@ -69,17 +69,17 @@ public:
 protected:
   virtual ~ArchiveZipFileImpl()
   {
     MOZ_COUNT_DTOR(ArchiveZipFileImpl);
   }
 
   virtual already_AddRefed<FileImpl>
   CreateSlice(uint64_t aStart, uint64_t aLength, const nsAString& aContentType,
-              ErrorResult& aRv) MOZ_OVERRIDE;
+              mozilla::ErrorResult& aRv) MOZ_OVERRIDE;
 
 private: // Data
   ZipCentral mCentral;
   nsRefPtr<ArchiveReader> mArchiveReader;
 
   nsString mFilename;
 };