diff --git a/core/modules/rest/src/Tests/Views/StyleSerializerTest.php b/core/modules/rest/src/Tests/Views/StyleSerializerTest.php
index 4b40a62396..5a2d77e370 100644
--- a/core/modules/rest/src/Tests/Views/StyleSerializerTest.php
+++ b/core/modules/rest/src/Tests/Views/StyleSerializerTest.php
@@ -351,7 +351,7 @@ public function testResponseFormatConfiguration() {
 
     // Test with no format.
     $this->drupalGet('test/serialize/field');
-    $this->assertHeader('content-type', 'application/json');
+    $this->assertHeader('content-type', 'text/html; charset=UTF-8');
     $this->assertResponse(406, 'A 406 response was returned when no format was requested.');
 
     // Select only 'xml' as an accepted format.