diff --git a/tests/fuzz/grant-client-credentials.yml b/tests/fuzz/grant-client-credentials.yml
index cc0e8519..e56d903f 100644
--- a/tests/fuzz/grant-client-credentials.yml
+++ b/tests/fuzz/grant-client-credentials.yml
@@ -41,6 +41,14 @@ request:
                 headers.content-type: "application/json"
                 body.error: unsupported_grant_type
                 #body.message: "The authorization grant type XXX is not supported by the authorization server."
+        -
+            key: scope
+            value: "basic"
+            invalid:
+                response.statusCode: 400
+                headers.content-type: "application/json"
+                body.error: invalid_scope
+                border.message: fooooooooo
 response:
     statusCode: 200
     headers: