diff --git a/test/lib/next-test-utils.ts b/test/lib/next-test-utils.ts
index 22ce39ae0b1c0..dfb6477df6b12 100644
--- a/test/lib/next-test-utils.ts
+++ b/test/lib/next-test-utils.ts
@@ -617,7 +617,7 @@ export async function check(
   for (let tries = 0; tries < maxRetries; tries++) {
     try {
       content = await contentFn()
-      if (!(regex instanceof RegExp)) {
+      if (typeof regex !== typeof /regex/) {
         if (regex === content) {
           return true
         }