diff --git a/tests/LocaleMiddlewareTest.php b/tests/LocaleMiddlewareTest.php
index d350d3f..de54aee 100644
--- a/tests/LocaleMiddlewareTest.php
+++ b/tests/LocaleMiddlewareTest.php
@@ -15,14 +15,33 @@ use Slim\Http\Response;
  */
 class LocaleMiddlewareTest extends \PHPUnit_Framework_TestCase
 {
+    /**
+     * Original locale.
+     *
+     * @var string
+     */
+    private $locale;
+
     /**
      * Prepare tests.
      */
     protected function setUp()
     {
+        $this->locale = getenv('LANG');
         $this->middleware = new LocaleMiddleware();
     }
 
+    /**
+     * Restore environment after the tests.
+     *
+     * @return void
+     */
+    protected function tearDown()
+    {
+        putenv('LANG='.$this->locale);
+        setlocale(LC_ALL, $this->locale);
+    }
+
     /**
      * Test the testLocale() function.
      *