diff --git a/composer.json b/composer.json
index 374fb92..456a429 100644
--- a/composer.json
+++ b/composer.json
@@ -11,10 +11,10 @@
         }
     ],
     "require": {
-        "php": ">=5.3.0"
+        "php": "^5.5.9|>=7.0.8"
     },
     "require-dev": {
-        "phpunit/phpunit": "4.8.*"
+        "phpunit/phpunit": "~4.8 || ^5.6"
     },
     "autoload": {
         "psr-4": {