diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index 1fc71b2..d350006 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -1415,10 +1415,10 @@ protected function curlHeaderCallback($curlHandler, $header) {
       call_user_func_array(array(&$this, 'error'), unserialize(urldecode($matches[1])));
     }
     if ($this->memoryUsageTrigger && preg_match('/^X-Drupal-Memory-Peak: (.*)$/', $header, $matches) && (float) $matches[1] >= Bytes::toInt($this->memoryUsageTrigger)) {
-      $this->fail(SafeMarkup::format('Child site memory usage (@site) exceeded acceptable maximum (@max) on url @url', [
+      $this->fail(SafeMarkup::format('Child site memory usage (@site_usage) exceeded acceptable maximum (@max_usage) on url @url', [
         '@url' => curl_getinfo($curlHandler, CURLINFO_EFFECTIVE_URL),
-        '@site' => format_size($matches[1]),
-        '@max' => $this->memoryUsageTrigger,
+        '@site_usage' => format_size($matches[1]),
+        '@max_usage' => $this->memoryUsageTrigger,
       ]));
     }