diff --git a/composer.json b/composer.json
index d7fa7c54..7d56d6e6 100644
--- a/composer.json
+++ b/composer.json
@@ -22,6 +22,9 @@
 		"silverstripe/reports": "*",
 		"silverstripe/siteconfig": "^4.0"
 	},
+	"require-dev": {
+		"phpunit/PHPUnit": "~4.8"
+	},
 	"extra": {
 		"branch-alias": {
 			"dev-master": "4.0.x-dev"