diff --git a/tests/composer.json b/tests/composer.json
index a3aa9972..98304617 100644
--- a/tests/composer.json
+++ b/tests/composer.json
@@ -25,7 +25,7 @@
     "forum": "http://www.smarty.net/forums/"
   },
   "require": {
-    "phpunit/phpunit": "~4",
+    "phpunit/phpunit": "~4@stable",
     "php": ">=5.2"
   },
   "autoload": {