diff --git a/composer.json b/composer.json
index 6107baf..fbd2d77 100644
--- a/composer.json
+++ b/composer.json
@@ -13,6 +13,9 @@
     "require": {
         "php": ">=5.3.0"
     },
+    "require-dev": {
+        "phpunit/phpunit": "^4.0"
+    },
     "autoload": {
         "psr-0": {
             "Igorw\\EventSource": "src"