--- a/dom/media/MediaFormatReader.cpp
+++ b/dom/media/MediaFormatReader.cpp
@@ -2049,17 +2049,18 @@ MediaFormatReader::UpdateReceivedNewData
     ScheduleSeek();
     return true;
   }
   if (decoder.HasInternalSeekPending() || decoder.HasWaitingPromise()) {
     if (decoder.HasInternalSeekPending()) {
       LOG("Attempting Internal Seek");
       InternalSeek(aTrack, decoder.mTimeThreshold.ref());
     }
-    if (decoder.HasWaitingPromise() && !decoder.IsWaiting()) {
+    if (decoder.HasWaitingPromise() && !decoder.IsWaitingForKey() &&
+        !decoder.IsWaitingForData()) {
       MOZ_ASSERT(!decoder.HasPromise());
       LOG("We have new data. Resolving WaitingPromise");
       decoder.mWaitingPromise.Resolve(decoder.mType, __func__);
     }
     return true;
   }
   return false;
 }
@@ -2555,19 +2556,19 @@ MediaFormatReader::Update(TrackType aTra
        IsDecoderWaitingForCDM(aTrack));
 
   if (IsWaitingOnCDMResource() || !ResolveSetCDMPromiseIfDone(aTrack)) {
     // If the content is encrypted, MFR won't start to create decoder until
     // CDMProxy is set.
     return;
   }
 
-  if ((decoder.mWaitingForData &&
+  if ((decoder.IsWaitingForData() &&
        (!decoder.mTimeThreshold || decoder.mTimeThreshold.ref().mWaiting)) ||
-      (decoder.mWaitingForKey && decoder.mDecodeRequest.Exists())) {
+      (decoder.IsWaitingForKey())) {
     // Nothing more we can do at present.
     LOGV("Still waiting for data or key. data(%d)/key(%d)",
          decoder.mWaitingForData,
          decoder.mWaitingForKey);
     return;
   }
 
   if (decoder.CancelWaitingForKey()) {
@@ -2652,17 +2653,17 @@ MediaFormatReader::SizeOfQueue(TrackType
 
 RefPtr<MediaFormatReader::WaitForDataPromise>
 MediaFormatReader::WaitForData(MediaData::Type aType)
 {
   MOZ_ASSERT(OnTaskQueue());
   TrackType trackType = aType == MediaData::VIDEO_DATA ?
     TrackType::kVideoTrack : TrackType::kAudioTrack;
   auto& decoder = GetDecoderData(trackType);
-  if (!decoder.IsWaiting()) {
+  if (!decoder.IsWaitingForData() && !decoder.IsWaitingForKey()) {
     // We aren't waiting for anything.
     return WaitForDataPromise::CreateAndResolve(decoder.mType, __func__);
   }
   RefPtr<WaitForDataPromise> p = decoder.mWaitingPromise.Ensure(__func__);
   ScheduleUpdate(trackType);
   return p;
 }
 

--- a/dom/media/MediaFormatReader.h
+++ b/dom/media/MediaFormatReader.h
@@ -416,20 +416,27 @@ private:
     // A WaitingPromise is pending if the demuxer is waiting for data or
     // if the decoder is waiting for a key.
     MozPromiseHolder<WaitForDataPromise> mWaitingPromise;
     bool HasWaitingPromise() const
     {
       MOZ_ASSERT(mOwner->OnTaskQueue());
       return !mWaitingPromise.IsEmpty();
     }
-    bool IsWaiting() const
+
+    bool IsWaitingForData() const
     {
       MOZ_ASSERT(mOwner->OnTaskQueue());
-      return mWaitingForData || mWaitingForKey;
+      return mWaitingForData;
+    }
+
+    bool IsWaitingForKey() const
+    {
+      MOZ_ASSERT(mOwner->OnTaskQueue());
+      return mWaitingForKey && mDecodeRequest.Exists();
     }
 
     // MediaDataDecoder handler's variables.
     MozPromiseRequestHolder<MediaDataDecoder::DecodePromise> mDecodeRequest;
     bool mFlushing; // True if flush is in action.
     // Set to true if the last operation run on the decoder was a flush.
     bool mFlushed;
     RefPtr<SharedShutdownPromiseHolder> mShutdownPromise;
@@ -516,17 +523,17 @@ private:
     void Flush();
 
     bool CancelWaitingForKey()
     {
       if (!mWaitingForKey) {
         return false;
       }
       mWaitingForKey = false;
-      if (IsWaiting() || !HasWaitingPromise()) {
+      if (IsWaitingForData() || !HasWaitingPromise()) {
         return false;
       }
       mWaitingPromise.Resolve(mType, __func__);
       return true;
     }
 
     // Reset the state of the DecoderData, clearing all queued frames
     // (pending demuxed and decoded).