diff --git a/composer.json b/composer.json
index 116e567..ea30938 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
         }
     },
     "require": {
-        "php": ">=5.3.23",
+        "php": ">=5.5",
         "zendframework/zend-math": "~2.5",
         "zendframework/zend-stdlib": "~2.5"
     },