diff --git a/composer.json b/composer.json
index 1ebe51d..6ae1e71 100644
--- a/composer.json
+++ b/composer.json
@@ -8,6 +8,6 @@
         "squizlabs/php_codesniffer": "3.3.2"
     },
     "require-dev": {
-        "phpunit/phpunit": "6.5.8"
+        "phpunit/phpunit": "6.5.13"
     }
 }