diff --git a/composer.json b/composer.json
index be925f2..60ee311 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
 	},
 	"minimum-stability": "stable",
 	"require-dev": {
-		"phpunit/phpunit": "~4.5.1"
+		"phpunit/phpunit": "~4.8.28"
 	},
 	"suggest": {
 		"ext-curl": "*"