diff --git a/composer.json b/composer.json
index 4bbdbbd..99bd01e 100644
--- a/composer.json
+++ b/composer.json
@@ -22,7 +22,8 @@
         "satooshi/php-coveralls": "dev-master"
     },
     "require": {
-        "php": ">=5.4"
+        "php": ">=5.4",
+        "league/oauth2-server": "3.*"
     },
     "autoload": {
         "psr-4": {