diff --git a/composer.json b/composer.json
index 8657969..f6a4ad8 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,7 @@
     "php": "^7.0.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "6.0",
+    "phpunit/phpunit": "6.5.14",
     "squizlabs/php_codesniffer": "3.*",
     "wp-coding-standards/wpcs": "1.2.0"
   },