diff --git a/README.md b/README.md
index a0fb2bf..531b985 100644
--- a/README.md
+++ b/README.md
@@ -39,7 +39,7 @@ require_once '[PATH/TO]/src/Spout/Autoloader/autoload.php'; // don't forget to c
 
 ## Requirements
 
-* PHP version 5.4.0 or higher
+* PHP version 5.6 or higher
 * PHP extension `php_zip` enabled
 * PHP extension `php_xmlreader` enabled
 
diff --git a/composer.json b/composer.json
index 76485c9..66f7a12 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
         }
     ],
     "require": {
-        "php": ">=5.4.0",
+        "php": ">=5.6.0",
         "ext-zip": "*",
         "ext-xmlreader" : "*"
     },