diff --git a/composer.json b/composer.json
index 9b57a0d..c733d77 100644
--- a/composer.json
+++ b/composer.json
@@ -9,11 +9,12 @@
   }
 
   "require": {
-
+    "php": ">=5.6.0"
   },
 
   "require-dev": {
     "phpunit/phpunit": "5.3.*",
-    "phpdocumentor/phpdocumentor": "2.8.*"
+    "phpdocumentor/phpdocumentor": "2.8.*",
+    "squizlabs/php_codesniffer": "2.*"
   }
 }