diff --git a/composer.json b/composer.json
index c6e096f..33fc7a0 100644
--- a/composer.json
+++ b/composer.json
@@ -45,6 +45,7 @@
         "twig/twig": "^1.0||^2.0"
     },
     "require-dev": {
+        "phpunit/phpunit": "6.*",
         "sensio/generator-bundle": "^3.0",
         "symfony/phpunit-bridge": "^3.0"
     },