diff --git a/lib/internal/process/pre_execution.js b/lib/internal/process/pre_execution.js
index f120f371d9b634..2be86f907bd47c 100644
--- a/lib/internal/process/pre_execution.js
+++ b/lib/internal/process/pre_execution.js
@@ -292,7 +292,8 @@ function setupUndici() {
   }
 
   if (!getOptionValue('--no-experimental-fetch')) {
-    async function fetch(input, init = undefined) {
+    // Fetch is meant to return a Promise, but not be async.
+    function fetch(input, init = undefined) {
       return lazyUndici().fetch(input, init);
     }
 
diff --git a/test/parallel/test-fetch.mjs b/test/parallel/test-fetch.mjs
index e24a38eb27db37..c1a030a7d2eac2 100644
--- a/test/parallel/test-fetch.mjs
+++ b/test/parallel/test-fetch.mjs
@@ -10,6 +10,12 @@ assert.strictEqual(typeof globalThis.Headers, 'function');
 assert.strictEqual(typeof globalThis.Request, 'function');
 assert.strictEqual(typeof globalThis.Response, 'function');
 
+{
+  const asyncFunction = async function() {}.constructor;
+
+  assert.ok(!(fetch instanceof asyncFunction));
+}
+
 const server = http.createServer(common.mustCall((req, res) => {
   res.end('Hello world');
 }));