diff --git a/composer.json b/composer.json
index 71d51b238..7b00e9fb1 100644
--- a/composer.json
+++ b/composer.json
@@ -16,6 +16,7 @@
         }
     ],
     "require": {
+        "php": "~5.5",
         "twig/extensions": "~1.0",
         "symfony/assetic-bundle": "~2.3",
         "symfony/monolog-bundle": "~2.4",