--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -376,18 +376,19 @@ public:
     // where mQueuedSeek must be empty.
     MOZ_ASSERT(!mMaster->mQueuedSeek.Exists());
 
     mPendingDormant = aPendingDormant;
   }
 
   void Exit() override
   {
-    // Transfer the seek job so it is available to the next state.
-    mMaster->mQueuedSeek = Move(mPendingSeek);
+    // mPendingSeek is either moved in HandleCDMProxyReady() or should be
+    // rejected here before transition to SHUTDOWN.
+    mPendingSeek.RejectIfExists(__func__);
   }
 
   State GetState() const override
   {
     return DECODER_STATE_WAIT_FOR_CDM;
   }
 
   bool HandleDormant(bool aDormant) override;