diff --git a/packages/ai/test/callback-server-port-fallback.test.ts b/packages/ai/test/callback-server-port-fallback.test.ts
index 65bdd5282..bfa3cd8cd 100644
--- a/packages/ai/test/callback-server-port-fallback.test.ts
+++ b/packages/ai/test/callback-server-port-fallback.test.ts
@@ -26,11 +26,13 @@ class TestCallbackFlow extends OAuthCallbackFlow {
 
 /**
  * Bind a real loopback port so the next `Bun.serve({ port })` against the
- * same port fails with EADDRINUSE. Returns the bound port plus a `release`
- * callback for teardown.
+ * same port fails with EADDRINUSE. Occupies `127.0.0.1` explicitly — the
+ * interface callback flows bind for `localhost` — because macOS lets a
+ * specific-address bind coexist with a wildcard one. Returns the bound port
+ * plus a `release` callback for teardown.
  */
 function occupyLoopbackPort(): { port: number; release: () => void } {
-	const server = Bun.serve({ port: 0, fetch: () => new Response("blocker") });
+	const server = Bun.serve({ hostname: "127.0.0.1", port: 0, fetch: () => new Response("blocker") });
 	const port = server.port;
 	if (typeof port !== "number") {
 		server.stop(true);