diff --git a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
index 095981e..4604118 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -714,11 +714,13 @@ abstract class TestBase {
     $this->public_files_directory = $this->originalFileDirectory . '/simpletest/' . substr($this->databasePrefix, 10);
     $this->private_files_directory = $this->public_files_directory . '/private';
     $this->temp_files_directory = $this->private_files_directory . '/temp';
+    $this->translation_files_directory = $this->public_files_directory . '/translations';
 
     // Create the directories
     file_prepare_directory($this->public_files_directory, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS);
     file_prepare_directory($this->private_files_directory, FILE_CREATE_DIRECTORY);
     file_prepare_directory($this->temp_files_directory, FILE_CREATE_DIRECTORY);
+    file_prepare_directory($this->translation_files_directory, FILE_CREATE_DIRECTORY);
     $this->generatedTestFiles = FALSE;
 
     // Create and set new configuration directories. The child site
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 385d6f4..8a6ae72 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -632,6 +632,7 @@ abstract class WebTestBase extends TestBase {
     variable_set('file_public_path', $this->public_files_directory);
     variable_set('file_private_path', $this->private_files_directory);
     variable_set('file_temporary_path', $this->temp_files_directory);
+    variable_set('locale_translate_file_directory', $this->translation_files_directory);
 
     // Set 'parent_profile' of simpletest to add the parent profile's
     // search path to the child site's search paths.