diff --git a/core/modules/hal/tests/src/Functional/HalJsonBasicAuthWorkaroundFor2805281Trait.php b/core/modules/hal/tests/src/Functional/HalJsonBasicAuthWorkaroundFor2805281Trait.php
index ef77d96..10ec699 100644
--- a/core/modules/hal/tests/src/Functional/HalJsonBasicAuthWorkaroundFor2805281Trait.php
+++ b/core/modules/hal/tests/src/Functional/HalJsonBasicAuthWorkaroundFor2805281Trait.php
@@ -20,7 +20,7 @@ protected function assertResponseWhenMissingAuthentication(ResponseInterface $re
     // @todo this works fine locally, but on testbot it comes back with
     // 'text/plain; charset=UTF-8'. WTF.
     // $this->assertSame(['application/hal+json'], $response->getHeader('Content-Type'));
-    $this->assertSame('No authentication credentials provided.', (string) $response->getBody());
+    $this->assertSame(json_encode(['message' => 'No authentication credentials provided.']), (string) $response->getBody());
   }
 
 }