diff --git a/composer.json b/composer.json
index 7daf82a..34017f7 100644
--- a/composer.json
+++ b/composer.json
@@ -35,7 +35,8 @@
     },
     "require-dev": {
         "phpunit/phpunit": "*",
-        "cakephp/cakephp-codesniffer": "dev-master"
+        "cakephp/cakephp-codesniffer": "dev-master",
+    "phpstan/phpstan": "^0.9.2"
     },
     "extra": {
     "installer-name": "CurrencyConverter"