diff --git a/composer.json b/composer.json
index 48144de..b8295be 100644
--- a/composer.json
+++ b/composer.json
@@ -3,7 +3,7 @@
     "type": "project",
     "license": "GPL-3.0",
     "require": {
-        "phpunit/phpunit": "8.4.3",
+        "phpunit/phpunit": "8.5.40",
         "league/flysystem": "1.0.57"
     },
     "autoload": {