diff --git a/composer.json b/composer.json
index 5b8542440..862dff494 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,7 @@
 		"php": ">=7.0.3"
 	},
 	"require-dev": {
-		"phpunit/phpunit": "6.0.*"
+		"phpunit/phpunit": "6.4.*"
 	},
 	"suggest": {
 		"chillerlan/php-googleauth": "*"