diff --git a/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php b/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
index 5ca7ca2..440ee36 100644
--- a/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
+++ b/core/modules/language/src/Tests/LanguageUILanguageNegotiationTest.php
@@ -503,7 +503,7 @@ public function testContentCustomization() {
     $this->assertTrue(in_array('language_content', $config->get('configurable')), 'Content language is configurable.');
 
     // Ensure configuration was saved.
-    $this->assertFalse(in_array('language-url', $config->get('negotiation.language_content.enabled')), 'URL negotiation is not enabled for content.');
-    $this->assertTrue(in_array('language-session', $config->get('negotiation.language_content.enabled')), 'Session negotiation is enabled for content.');
+    $this->assertFalse(array_key_exists('language-url', $config->get('negotiation.language_content.enabled')), 'URL negotiation is not enabled for content.');
+    $this->assertTrue(array_key_exists('language-session', $config->get('negotiation.language_content.enabled')), 'Session negotiation is enabled for content.');
   }
 }