diff --git a/packages/desktop/scripts/managed-daemon-smoke.mjs b/packages/desktop/scripts/managed-daemon-smoke.mjs
index 91edd97cf..2eca7d71b 100644
--- a/packages/desktop/scripts/managed-daemon-smoke.mjs
+++ b/packages/desktop/scripts/managed-daemon-smoke.mjs
@@ -487,10 +487,17 @@ let externalPid = null;
 let startedTemporaryExternalDaemon = false;
 let relayProcess = null;
 const forbiddenManagedReferences = ["127.0.0.1:6767", fakePaseoHome, managedRuntimeDir];
+const npmExecPath = process.env.npm_execpath;
+if (!npmExecPath) {
+  throw new Error("npm_execpath is required to launch wrangler during managed desktop smoke tests.");
+}
 
 try {
   logStep(`Starting isolated local relay on ${relayEndpoint}`);
-  relayProcess = spawn(process.platform === "win32" ? "npx.cmd" : "npx", [
+  relayProcess = spawn(process.execPath, [
+    npmExecPath,
+    "exec",
+    "--",
     "wrangler",
     "dev",
     "--local",