diff --git a/Gruntfile.js b/Gruntfile.js
index 199f9faa2c..7cda785b56 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -464,6 +464,10 @@ module.exports = function(grunt) {
 				cmd: 'phpunit',
 				args: ['--verbose', '-c', 'tests/phpunit/multisite.xml']
 			},
+			'ms-files': {
+				cmd: 'phpunit',
+				args: ['--verbose', '-c', 'tests/phpunit/multisite.xml', '--group', 'ms-files']
+			},
 			'external-http': {
 				cmd: 'phpunit',
 				args: ['--verbose', '-c', 'phpunit.xml.dist', '--group', 'external-http']