diff --git a/dom/workers/ScriptLoader.cpp b/dom/workers/ScriptLoader.cpp
index a837cf982ca0..3fa4b8c2ae54 100644
--- a/dom/workers/ScriptLoader.cpp
+++ b/dom/workers/ScriptLoader.cpp
@@ -240,6 +240,10 @@ struct ScriptLoadInfo
   // resolution.
   RefPtr<Promise> mCachePromise;
 
+  // The reader stream the cache entry should be filled from, for those cases
+  // when we're going to have an mCachePromise.
+  nsCOMPtr<nsIInputStream> mCacheReadStream;
+
   nsCOMPtr<nsIChannel> mChannel;
   char16_t* mScriptTextBuf;
   size_t mScriptTextLength;
@@ -534,7 +538,6 @@ class ScriptLoaderRunnable final : public WorkerFeature
   nsCOMPtr<nsIEventTarget> mSyncLoopTarget;
   nsTArray<ScriptLoadInfo> mLoadInfos;
   RefPtr<CacheCreator> mCacheCreator;
-  nsCOMPtr<nsIInputStream> mReader;
   bool mIsMainScript;
   WorkerScriptType mWorkerScriptType;
   bool mCanceled;
@@ -641,7 +644,10 @@ private:
     // We synthesize the result code, but its never exposed to content.
     RefPtr<mozilla::dom::InternalResponse> ir =
       new mozilla::dom::InternalResponse(200, NS_LITERAL_CSTRING("OK"));
-    ir->SetBody(mReader);
+    ir->SetBody(loadInfo.mCacheReadStream);
+    // Drop our reference to the stream now that we've passed it along, so it
+    // doesn't hang around once the cache is done with it and keep data alive.
+    loadInfo.mCacheReadStream = nullptr;
 
     // Set the channel info of the channel on the response so that it's
     // saved in the cache.
@@ -917,7 +923,8 @@ private:
       // In case we return early.
       loadInfo.mCacheStatus = ScriptLoadInfo::Cancel;
 
-      rv = NS_NewPipe(getter_AddRefs(mReader), getter_AddRefs(writer), 0,
+      rv = NS_NewPipe(getter_AddRefs(loadInfo.mCacheReadStream),
+                      getter_AddRefs(writer), 0,
                       UINT32_MAX, // unlimited size to avoid writer WOULD_BLOCK case
                       true, false); // non-blocking reader, blocking writer
       if (NS_WARN_IF(NS_FAILED(rv))) {