diff --git a/dom/media/gmp/GMPDecryptorParent.cpp b/dom/media/gmp/GMPDecryptorParent.cpp
index 41631e6d9824..18ecce8d55ab 100644
--- a/dom/media/gmp/GMPDecryptorParent.cpp
+++ b/dom/media/gmp/GMPDecryptorParent.cpp
@@ -16,8 +16,11 @@ GMPDecryptorParent::GMPDecryptorParent(GMPParent* aPlugin)
   , mShuttingDown(false)
   , mPlugin(aPlugin)
   , mCallback(nullptr)
+#ifdef DEBUG
+  , mGMPThread(aPlugin->GMPThread())
+#endif
 {
-  MOZ_ASSERT(mPlugin);
+  MOZ_ASSERT(mPlugin && mGMPThread);
 }
 
 GMPDecryptorParent::~GMPDecryptorParent()
@@ -312,7 +315,7 @@ GMPDecryptorParent::RecvDecrypted(const uint32_t& aId,
 void
 GMPDecryptorParent::Close()
 {
-  MOZ_ASSERT(mPlugin->GMPThread() == NS_GetCurrentThread());
+  MOZ_ASSERT(mGMPThread == NS_GetCurrentThread());
   // Consumer is done with us; we can shut down.  No more callbacks should
   // be made to mCallback. Note: do this before Shutdown()!
   mCallback = nullptr;
@@ -320,14 +323,14 @@ GMPDecryptorParent::Close()
 
   // In case this is the last reference
   nsRefPtr<GMPDecryptorParent> kungfudeathgrip(this);
-  NS_RELEASE(kungfudeathgrip);
+  this->Release();
   Shutdown();
 }
 
 void
 GMPDecryptorParent::Shutdown()
 {
-  MOZ_ASSERT(mPlugin->GMPThread() == NS_GetCurrentThread());
+  MOZ_ASSERT(mGMPThread == NS_GetCurrentThread());
 
   if (mShuttingDown) {
     return;
diff --git a/dom/media/gmp/GMPDecryptorParent.h b/dom/media/gmp/GMPDecryptorParent.h
index 987c17358cbf..5cc1d8461f6d 100644
--- a/dom/media/gmp/GMPDecryptorParent.h
+++ b/dom/media/gmp/GMPDecryptorParent.h
@@ -109,6 +109,9 @@ private:
   bool mShuttingDown;
   nsRefPtr<GMPParent> mPlugin;
   GMPDecryptorProxyCallback* mCallback;
+#ifdef DEBUG
+  nsIThread* const mGMPThread;
+#endif
 };
 
 } // namespace gmp