--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -1890,24 +1890,26 @@ MediaDecoder::NextFrameBufferedStatus()
     : MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE;
 }
 
 void
 MediaDecoder::DumpDebugInfo()
 {
   MOZ_ASSERT(!IsShutdown());
   DUMP_LOG("metadata: channels=%u rate=%u hasAudio=%d hasVideo=%d, "
-           "state: mPlayState=%s mIsDormant=%d",
+           "state: mPlayState=%s mIsDormant=%d, mdsm=%p",
            mInfo ? mInfo->mAudio.mChannels : 0, mInfo ? mInfo->mAudio.mRate : 0,
            mInfo ? mInfo->HasAudio() : 0, mInfo ? mInfo->HasVideo() : 0,
-           PlayStateStr(), mIsDormant);
+           PlayStateStr(), mIsDormant, GetStateMachine());
 
   nsString str;
   GetMozDebugReaderData(str);
-  DUMP_LOG("reader data:\n%s", NS_ConvertUTF16toUTF8(str).get());
+  if (!str.IsEmpty()) {
+    DUMP_LOG("reader data:\n%s", NS_ConvertUTF16toUTF8(str).get());
+  }
 
   if (GetStateMachine()) {
     GetStateMachine()->DumpDebugInfo();
   }
 }
 
 void
 MediaDecoder::NotifyAudibleStateChanged()