diff --git a/core/modules/config/src/Tests/ConfigImportUITest.php b/core/modules/config/src/Tests/ConfigImportUITest.php
index 31654b357744de1d63778b35e381c42d4f703ce8..772dadadd2dcf5a59fdb8ef3940a2236ba98724d 100644
--- a/core/modules/config/src/Tests/ConfigImportUITest.php
+++ b/core/modules/config/src/Tests/ConfigImportUITest.php
@@ -290,6 +290,7 @@ public function testImportDiff() {
 
     // Load the diff UI and verify that the diff reflects the change.
     $this->drupalGet('admin/config/development/configuration/sync/diff/' . $config_name);
+    $this->assertNoRaw(' ');
     $this->assertTitle(format_string('View changes of @config_name | Drupal', ['@config_name' => $config_name]));
 
     // The following assertions do not use $this::assertEscaped() because