diff --git a/composer.json b/composer.json
index 20b92514..94135c1d 100644
--- a/composer.json
+++ b/composer.json
@@ -22,6 +22,9 @@
 		"silverstripe/reports": "~3.4",
 		"silverstripe/siteconfig": "~3.4"
 	},
+	"require-dev": {
+		"phpunit/phpunit": "^3 || ^4 || ^5"
+	},
 	"extra": {
 		"branch-alias": {
 			"3.x-dev": "3.6.x-dev"