diff --git a/tools/nix/ci-shell.nix b/tools/nix/ci-shell.nix
index 07dc2299f41..c46d0d68c02 100644
--- a/tools/nix/ci-shell.nix
+++ b/tools/nix/ci-shell.nix
@@ -9,6 +9,10 @@ args@{
     loadJSBuiltinsDynamically = false;
     devTools = [ ];
     benchmarkTools = [ ];
+    extraConfigFlags = [
+      "--debug-node"
+      "--error-on-warn"
+    ];
   }
   // pkgs.lib.optionalAttrs pkgs.stdenv.hostPlatform.isDarwin (
     # Disable optional features on Darwin for coverage and faster CI.
@@ -20,6 +24,7 @@ args@{
     // {
       withSSL = true; # no-SSL coverage is ensured by Jenkins
       extraConfigFlags = [
+        "--error-on-warn"
         "--without-inspector"
         "--without-node-options"
       ];