diff --git a/nix/pkgs/lightspeed/lightspeed-react/default.nix b/nix/pkgs/lightspeed/lightspeed-react/default.nix
index ef1266057a..4687fa181a 100644
--- a/nix/pkgs/lightspeed/lightspeed-react/default.nix
+++ b/nix/pkgs/lightspeed/lightspeed-react/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, pkgs, fetchgit, nodejs }:
+{ stdenv, pkgs, fetchgit, nodejs, websocketURL ? "ws://stream.gud.software:8080/websocket" }:
 
 let
   nodePackages = import ./node-packages.nix {
@@ -23,6 +23,8 @@ stdenv.mkDerivation {
 
   patchPhase = ''
     find . -name '.DS_Store' -delete
+    substituteInPlace src/wsUrl.js \
+      --replace 'ws://stream.gud.software:8080/websocket' '${websocketURL}'
   '';
 
   buildPhase = ''