diff --git a/dom/html/HTMLMediaElement.cpp b/dom/html/HTMLMediaElement.cpp
index 5a4377d14053..9644b24e4cce 100644
--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -3205,7 +3205,13 @@ nsresult HTMLMediaElement::FinishDecoderSetup(MediaDecoder* aDecoder,
 
 #ifdef MOZ_EME
   if (mMediaKeys) {
-    mDecoder->SetCDMProxy(mMediaKeys->GetCDMProxy());
+    if (mMediaKeys->GetCDMProxy()) {
+      mDecoder->SetCDMProxy(mMediaKeys->GetCDMProxy());
+    } else {
+      // CDM must have crashed.
+      ShutdownDecoder();
+      return NS_ERROR_FAILURE;
+    }
   }
 #endif
 
@@ -5496,6 +5502,12 @@ HTMLMediaElement::SetMediaKeys(mozilla::dom::MediaKeys* aMediaKeys,
 
   // 5.3. If mediaKeys is not null, run the following steps:
   if (aMediaKeys) {
+    if (!aMediaKeys->GetCDMProxy()) {
+      promise->MaybeReject(NS_ERROR_DOM_INVALID_STATE_ERR,
+        NS_LITERAL_CSTRING("CDM crashed before binding MediaKeys object to HTMLMediaElement"));
+      return promise.forget();
+    }
+
     // 5.3.1 Associate the CDM instance represented by mediaKeys with the
     // media element for decrypting media data.
     if (NS_FAILED(aMediaKeys->Bind(this))) {
diff --git a/dom/media/MediaDecoder.cpp b/dom/media/MediaDecoder.cpp
index 52150986eb96..61d74ce6a9c2 100644
--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -1713,6 +1713,7 @@ void
 MediaDecoder::SetCDMProxy(CDMProxy* aProxy)
 {
   MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aProxy);
 
   mCDMProxyPromiseHolder.ResolveIfExists(aProxy, __func__);
 }