diff --git a/composer.json b/composer.json
index b131d04..50a0ed3 100644
--- a/composer.json
+++ b/composer.json
@@ -23,6 +23,7 @@
         "payum/core": "~1.0"
     },
     "require-dev": {
+        "payum/core": "~1.0@dev",
         "phpunit/phpunit": "~4.0",
         "php-http/guzzle6-adapter": "^1.0",
         "symfony/phpunit-bridge": "~2.8|~3.0"