diff --git a/composer.json b/composer.json
index 572112d..8a9255b 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
         }
     ],
     "require": {
-        "php" : "~5.5|~7.0"
+        "php" : "~5.6|~7.0"
     },
     "require-dev": {
         "phpunit/phpunit" : "~4.0||~5.0",