diff --git a/composer.json b/composer.json
index d72c026..a25524e 100644
--- a/composer.json
+++ b/composer.json
@@ -9,7 +9,8 @@
 	},
 	"require-dev": {
 		"silverstripe/compass": "*",
-		"silverstripe/docsviewer": "*"
+		"silverstripe/docsviewer": "*",
+		"phpunit/phpunit": "3.7.*"
 	},
 	"minimum-stability": "dev"
 }