diff --git a/dom/fetch/Fetch.h b/dom/fetch/Fetch.h
index 7b52dfdc62..0dcf1d859c 100644
--- a/dom/fetch/Fetch.h
+++ b/dom/fetch/Fetch.h
@@ -100,6 +100,8 @@ public:
   NS_IMETHOD_(MozExternalRefCountType) Release(void) = 0;
 
   virtual void NullifyStream() = 0;
+
+  virtual JSObject* ReadableStreamBody() = 0;
 };
 
 /*
@@ -228,6 +230,13 @@ public:
     mFetchStreamReader = nullptr;
   }
 
+  JSObject*
+  ReadableStreamBody() override
+  {
+    MOZ_ASSERT(mReadableStreamBody);
+    return mReadableStreamBody;
+  }
+
   virtual AbortSignal*
   GetSignal() const = 0;
 
diff --git a/dom/fetch/FetchStream.cpp b/dom/fetch/FetchStream.cpp
index ec224e1c8d..63e6f150b9 100644
--- a/dom/fetch/FetchStream.cpp
+++ b/dom/fetch/FetchStream.cpp
@@ -161,8 +161,6 @@ FetchStream::Create(JSContext* aCx, FetchStreamHolder* aStreamHolder,
     return;
   }
 
-  stream->mReadableStream = body;
-
   // This will be released in FetchStream::FinalizeCallback().  We are
   // guaranteed the jsapi will call FinalizeCallback when ReadableStream
   // js object is finalized.
@@ -371,7 +369,6 @@ FetchStream::FetchStream(nsIGlobalObject* aGlobal,
   , mStreamHolder(aStreamHolder)
   , mOriginalInputStream(aInputStream)
   , mOwningEventTarget(nullptr)
-  , mReadableStream(nullptr)
 {
   MOZ_DIAGNOSTIC_ASSERT(aInputStream);
   MOZ_DIAGNOSTIC_ASSERT(aStreamHolder);
@@ -428,7 +425,7 @@ FetchStream::OnInputStreamReady(nsIAsyncInputStream* aStream)
   }
 
   JSContext* cx = jsapi.cx();
-  JS::Rooted<JSObject*> stream(cx, mReadableStream);
+  JS::Rooted<JSObject*> stream(cx, mStreamHolder->ReadableStreamBody());
 
   uint64_t size = 0;
   nsresult rv = mInputStream->Available(&size);
@@ -494,7 +491,7 @@ FetchStream::Close()
   }
 
   JSContext* cx = jsapi.cx();
-  JS::Rooted<JSObject*> stream(cx, mReadableStream);
+  JS::Rooted<JSObject*> stream(cx, mStreamHolder->ReadableStreamBody());
 
   CloseAndReleaseObjects(cx, stream);
 }
diff --git a/dom/fetch/FetchStream.h b/dom/fetch/FetchStream.h
index 4562b3f351..80d120616d 100644
--- a/dom/fetch/FetchStream.h
+++ b/dom/fetch/FetchStream.h
@@ -125,8 +125,6 @@ private:
   nsCOMPtr<nsIAsyncInputStream> mInputStream;
 
   UniquePtr<workers::WorkerHolder> mWorkerHolder;
-
-  JS::Heap<JSObject*> mReadableStream;
 };
 
 } // dom namespace