diff --git a/composer.json b/composer.json
index bcb5752a7..a49eaf643 100644
--- a/composer.json
+++ b/composer.json
@@ -20,6 +20,9 @@
 	"require": {
 		"php": ">=5.6.0"
 	},
+	"require-dev": {
+		"phpunit/phpunit": "5.1.*"
+	},
 	"suggest": {
 		"chillerlan/php-googleauth": "*"
 	},