--- a/gfx/thebes/gfxDWriteCommon.cpp
+++ b/gfx/thebes/gfxDWriteCommon.cpp
@@ -3,16 +3,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "gfxDWriteCommon.h"
 
 #include <unordered_map>
 
 #include "mozilla/Atomics.h"
+#include "mozilla/gfx/Logging.h"
 
 static mozilla::Atomic<uint64_t> sNextFontFileKey;
 static std::unordered_map<uint64_t, IDWriteFontFileStream*> sFontFileStreams;
 
 IDWriteFontFileLoader* gfxDWriteFontFileLoader::mInstance = nullptr;
 
 class gfxDWriteFontFileStream final : public IDWriteFontFileStream
 {
@@ -153,16 +154,20 @@ HRESULT
 gfxDWriteFontFileLoader::CreateCustomFontFile(FallibleTArray<uint8_t>& aFontData,
                                               IDWriteFontFile** aFontFile,
                                               IDWriteFontFileStream** aFontFileStream)
 {
   MOZ_ASSERT(aFontFile);
   MOZ_ASSERT(aFontFileStream);
 
   IDWriteFactory *factory = gfxWindowsPlatform::GetPlatform()->GetDWriteFactory();
+  if (!factory) {
+    gfxCriticalError() << "Failed to get DWrite Factory in CreateCustomFontFile.";
+    return E_FAIL;
+  }
 
   uint64_t fontFileKey = sNextFontFileKey++;
   RefPtr<IDWriteFontFileStream> ffsRef = new gfxDWriteFontFileStream(&aFontData, fontFileKey);
   sFontFileStreams[fontFileKey] = ffsRef;
 
   RefPtr<IDWriteFontFile> fontFile;
   HRESULT hr = factory->CreateCustomFontFileReference(&fontFileKey, sizeof(fontFileKey), Instance(), getter_AddRefs(fontFile));
   if (FAILED(hr)) {