--- a/netwerk/protocol/http/nsCORSListenerProxy.cpp
+++ b/netwerk/protocol/http/nsCORSListenerProxy.cpp
@@ -1031,23 +1031,16 @@ nsCORSListenerProxy::CheckPreflightNeede
     headers.AppendElement(NS_LITERAL_CSTRING("content-type"));
     doPreflight = true;
   }
 
   if (!doPreflight) {
     return NS_OK;
   }
 
-  // A preflight is needed. But if we've already been cross-site, then
-  // we already did a preflight when that happened, and so we're not allowed
-  // to do another preflight again.
-  if (aUpdateType != UpdateType::InternalOrHSTSRedirect) {
-    NS_ENSURE_FALSE(mHasBeenCrossSite, NS_ERROR_DOM_BAD_URI);
-  }
-
   nsCOMPtr<nsIHttpChannelInternal> internal = do_QueryInterface(http);
   NS_ENSURE_TRUE(internal, NS_ERROR_DOM_BAD_URI);
 
   internal->SetCorsPreflightParameters(
     headers.IsEmpty() ? loadInfoHeaders : headers);
 
   return NS_OK;
 }