diff --git a/exercises/isbn-verifier/isbn-verifier.spec.js b/exercises/isbn-verifier/isbn-verifier.spec.js
index b6f4349498..c7141c922d 100644
--- a/exercises/isbn-verifier/isbn-verifier.spec.js
+++ b/exercises/isbn-verifier/isbn-verifier.spec.js
@@ -32,7 +32,7 @@ describe('ISBN Verifier Test Suite', () => {
   });
 
   xtest('X is only valid as a check digit', () => {
-    const isbn = new ISBN('3-598-2X507-0');
+    const isbn = new ISBN('3-598-2X507-9');
 
     expect(isbn.isValid()).toEqual(false);
   });