--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -1673,19 +1673,16 @@ MediaDecoderStateMachine::SetState(State
       mStateObj = MakeUnique<DormantState>(this);
       break;
     case DECODER_STATE_DECODING_FIRSTFRAME:
       mStateObj = MakeUnique<DecodingFirstFrameState>(this);
       break;
     case DECODER_STATE_DECODING:
       mStateObj = MakeUnique<DecodingState>(this);
       break;
-    case DECODER_STATE_SEEKING:
-      mStateObj = MakeUnique<SeekingState>(this);
-      break;
     case DECODER_STATE_BUFFERING:
       mStateObj = MakeUnique<BufferingState>(this);
       break;
     case DECODER_STATE_COMPLETED:
       mStateObj = MakeUnique<CompletedState>(this);
       break;
     case DECODER_STATE_SHUTDOWN:
       mStateObj = MakeUnique<ShutdownState>(this);
@@ -2110,17 +2107,22 @@ MediaDecoderStateMachine::DispatchDecode
   }
 }
 
 void
 MediaDecoderStateMachine::InitiateSeek(SeekJob aSeekJob)
 {
   MOZ_ASSERT(OnTaskQueue());
 
-  SetState(DECODER_STATE_SEEKING);
+  // Note we can't call SetState(DECODER_STATE_SEEKING) which does nothing
+  // if we are already in the SEEKING state.
+  mStateObj->Exit();
+  mState = DECODER_STATE_SEEKING;
+  mStateObj = MakeUnique<SeekingState>(this);
+  mStateObj->Enter();
 
   // Discard the existing seek task.
   DiscardSeekTaskIfExist();
 
   mSeekTaskRequest.DisconnectIfExists();
 
   // SeekTask will register its callbacks to MediaDecoderReaderWrapper.
   CancelMediaDecoderReaderWrapperCallback();