diff --git a/netwerk/protocol/http/HttpChannelParent.cpp b/netwerk/protocol/http/HttpChannelParent.cpp
index 8391d9674ac2..d0ae23c391a0 100644
--- a/netwerk/protocol/http/HttpChannelParent.cpp
+++ b/netwerk/protocol/http/HttpChannelParent.cpp
@@ -968,11 +968,6 @@ HttpChannelParent::DivertTo(nsIStreamListener *aListener)
 
   mDivertListener = aListener;
 
-  if (NS_WARN_IF(mIPCClosed || !SendFlushedForDiversion())) {
-    FailDiversion(NS_ERROR_UNEXPECTED);
-    return;
-  }
-
   // Call OnStartRequest and SendDivertMessages asynchronously to avoid
   // reentering client context.
   NS_DispatchToCurrentThread(
@@ -1020,6 +1015,11 @@ HttpChannelParent::StartDiversion()
   MOZ_ASSERT(NS_SUCCEEDED(rvdbg));
   mDivertListener = nullptr;
 
+  if (NS_WARN_IF(mIPCClosed || !SendFlushedForDiversion())) {
+    FailDiversion(NS_ERROR_UNEXPECTED);
+    return;
+  }
+
   // The listener chain should now be setup; tell HttpChannelChild to divert
   // the OnDataAvailables and OnStopRequest to this HttpChannelParent.
   if (NS_WARN_IF(mIPCClosed || !SendDivertMessages())) {