diff --git a/src/D8/EmailTrait.php b/src/D8/EmailTrait.php
index 1995da46..9c4bbdae 100644
--- a/src/D8/EmailTrait.php
+++ b/src/D8/EmailTrait.php
@@ -136,7 +136,7 @@ public function emailAssertEmailContains($field, PyStringNode $string, $exact =
     $string = strval($string);
     $string = $exact ? $string : trim(preg_replace('/\s+/', ' ', $string));
     foreach (self::emailGetCollectedEmails() as $email) {
-      $field_string = $email['params'][$field] ?? $email[$field];
+      $field_string = $email[$field] ?? '';
       $field_string = $exact ? $field_string : trim(preg_replace('/\s+/', ' ', $field_string));
       if (strpos($field_string, $string) !== FALSE) {
         return $email;
diff --git a/tests/behat/fixtures/d8/docroot/modules/custom/mysite_core/mysite_core.module b/tests/behat/fixtures/d8/docroot/modules/custom/mysite_core/mysite_core.module
index 2a4a86e2..89f8edc5 100644
--- a/tests/behat/fixtures/d8/docroot/modules/custom/mysite_core/mysite_core.module
+++ b/tests/behat/fixtures/d8/docroot/modules/custom/mysite_core/mysite_core.module
@@ -24,4 +24,5 @@ function mysite_core_mail($key, &$message, $params) {
       $message['subject'] = t('Test Email');
       break;
   }
+  $message['body'][] = strval($params['body']) ?? '';
 }