--- a/uriloader/preload/PreloaderBase.cpp
+++ b/uriloader/preload/PreloaderBase.cpp
@@ -162,21 +162,24 @@ void PreloaderBase::NotifyRestart(dom::D
   mKey = PreloadHashKey();
 
   if (aNewPreloader) {
     aNewPreloader->mNodes = std::move(mNodes);
   }
 }
 
 void PreloaderBase::NotifyStart(nsIRequest* aRequest) {
-  if (!SameCOMIdentity(aRequest, mChannel)) {
+  // If there is no channel assigned on this preloader, we are not between
+  // channel switching, so we can freely update the mShouldFireLoadEvent using
+  // the given channel.
+  if (mChannel && !SameCOMIdentity(aRequest, mChannel)) {
     return;
   }
 
-  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(mChannel);
+  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aRequest);
   if (!httpChannel) {
     return;
   }
 
   // if the load is cross origin without CORS, or the CORS access is rejected,
   // always fire load event to avoid leaking site information.
   nsresult rv;
   nsCOMPtr<nsILoadInfo> loadInfo = httpChannel->LoadInfo();