diff --git a/modules/simpletest/drupal_web_test_case.php b/modules/simpletest/drupal_web_test_case.php
index 40af458..d2a90da 100644
--- a/modules/simpletest/drupal_web_test_case.php
+++ b/modules/simpletest/drupal_web_test_case.php
@@ -1255,6 +1255,11 @@ class DrupalWebTestCase extends DrupalTestCase {
     $this->originalProfile = drupal_get_profile();
     $clean_url_original = variable_get('clean_url', 0);
 
+    // Set to English to prevent exceptions from utf8_truncate() from t()
+    // during install if the current language is not 'en'.
+    // Object convertion the same as language_default().
+    $language = (object) array('language' => 'en', 'name' => 'English', 'native' => 'English', 'direction' => 0, 'enabled' => 1, 'plurals' => 0, 'formula' => '', 'domain' => '', 'prefix' => '', 'weight' => 0, 'javascript' => '');
+
     // Save and clean shutdown callbacks array because it static cached and
     // will be changed by the test run. If we don't, then it will contain
     // callbacks from both environments. So testing environment will try