diff --git a/core/tests/Drupal/Nightwatch/Assertions/deprecationErrorExists.js b/core/tests/Drupal/Nightwatch/Assertions/deprecationErrorExists.js
index 0b8b9f64f56..e1afee8ea78 100644
--- a/core/tests/Drupal/Nightwatch/Assertions/deprecationErrorExists.js
+++ b/core/tests/Drupal/Nightwatch/Assertions/deprecationErrorExists.js
@@ -7,7 +7,7 @@ module.exports.assertion = function (expected) {
     const deprecationMessages =
       sessionStorageEntries !== null
         ? sessionStorageEntries.filter((message) =>
-            new RegExp('[Deprecation]').test(message),
+            message.includes('[Deprecation]'),
           )
         : [];
 
diff --git a/core/tests/Drupal/Nightwatch/Assertions/noDeprecationErrors.js b/core/tests/Drupal/Nightwatch/Assertions/noDeprecationErrors.js
index 8d5ab79b9e8..2fb004e64f2 100644
--- a/core/tests/Drupal/Nightwatch/Assertions/noDeprecationErrors.js
+++ b/core/tests/Drupal/Nightwatch/Assertions/noDeprecationErrors.js
@@ -7,7 +7,7 @@ module.exports.assertion = function () {
     const deprecationMessages =
       sessionStorageEntries !== null
         ? sessionStorageEntries.filter((message) =>
-            new RegExp('[Deprecation]').test(message),
+            message.includes('[Deprecation]'),
           )
         : [];