diff --git a/composer.json b/composer.json
index cbed10f..31f99c4 100644
--- a/composer.json
+++ b/composer.json
@@ -17,6 +17,9 @@
     "require": {
         "php": ">=5.3.0"
     },
+    "require-dev": {
+        "phpunit/phpunit": "4.0.*"
+    },    
     "support": {
         "issues": "https://github.com/danielstjules/Stringy/issues",
         "source": "https://github.com/danielstjules/Stringy"