diff --git a/composer.json b/composer.json
index 6477e13..ae671f9 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,7 @@
     "maglnet/composer-require-checker": "^2.1",
     "nikic/php-parser": "^4.6",
     "php-parallel-lint/php-parallel-lint": "^1.2",
-    "phpro/grumphp-shim": "^0.19.0",
+    "phpro/grumphp-shim": "^0.19.0 || ^0.21.0",
     "phpstan/phpstan": "^0.12.32",
     "roave/security-advisories": "dev-master",
     "sensiolabs/security-checker": "^6.0"