diff --git a/composer.json b/composer.json
index a2447af3..e5469d80 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,7 @@
         }
     },
     "require-dev": {
-        "phpunit/phpunit": "~4.3"
+        "phpunit/phpunit": "~4.8.16"
     },
     "scripts": {
         "test": "phpunit"