diff --git a/dom/fetch/Fetch.cpp b/dom/fetch/Fetch.cpp
index d7a96fd35ae..1a875a2af18 100644
--- a/dom/fetch/Fetch.cpp
+++ b/dom/fetch/Fetch.cpp
@@ -241,6 +241,11 @@ FetchRequest(nsIGlobalObject* aGlobal, const RequestOrUSVString& aInput,
   } else {
     WorkerPrivate* worker = GetCurrentThreadWorkerPrivate();
     MOZ_ASSERT(worker);
+
+    if (worker->IsServiceWorker()) {
+      r->SetSkipServiceWorker();
+    }
+
     nsRefPtr<MainThreadFetchRunnable> run = new MainThreadFetchRunnable(worker, p, r);
     if (NS_FAILED(NS_DispatchToMainThread(run))) {
       NS_WARNING("MainThreadFetchRunnable dispatch failed!");
diff --git a/dom/fetch/FetchDriver.cpp b/dom/fetch/FetchDriver.cpp
index f8109db0f45..31462cf3b33 100644
--- a/dom/fetch/FetchDriver.cpp
+++ b/dom/fetch/FetchDriver.cpp
@@ -8,6 +8,7 @@
 #include "nsIInputStream.h"
 #include "nsIOutputStream.h"
 #include "nsIHttpChannel.h"
+#include "nsIHttpChannelInternal.h"
 #include "nsIHttpHeaderVisitor.h"
 #include "nsIScriptSecurityManager.h"
 #include "nsIThreadRetargetableRequest.h"
@@ -450,6 +451,14 @@ FetchDriver::HttpFetch(bool aCORSFlag, bool aCORSPreflightFlag, bool aAuthentica
     }
   }
 
+  // Set skip serviceworker flag.
+  // While the spec also gates on the client being a ServiceWorker, we can't
+  // infer that here. Instead we rely on callers to set the flag correctly.
+  if (mRequest->SkipServiceWorker()) {
+    nsCOMPtr<nsIHttpChannelInternal> internalChan = do_QueryInterface(httpChan);
+    internalChan->ForceNoIntercept();
+  }
+
   // Set up a CORS proxy that will handle the various requirements of the CORS
   // protocol. It handles the preflight cache and CORS response headers.
   // If the request is allowed, it will start our original request
diff --git a/dom/fetch/InternalRequest.h b/dom/fetch/InternalRequest.h
index 2fa4324d256..6e19fc1d9d2 100644
--- a/dom/fetch/InternalRequest.h
+++ b/dom/fetch/InternalRequest.h
@@ -179,6 +179,18 @@ public:
     mReferrer.Assign(aReferrer);
   }
 
+  bool
+  SkipServiceWorker() const
+  {
+    return mSkipServiceWorker;
+  }
+
+  void
+  SetSkipServiceWorker()
+  {
+    mSkipServiceWorker = true;
+  }
+
   bool
   IsSynchronous() const
   {