diff --git a/composer.json b/composer.json
index c026e53e17d8..58aea5734b60 100644
--- a/composer.json
+++ b/composer.json
@@ -23,7 +23,7 @@
         "phpstan/phpdoc-parser": "^0.4",
         "phpstan/phpstan": "^0.12.9",
         "phpstan/phpstan-phpunit": "^0.12",
-        "sebastian/diff": "^3.0",
+        "sebastian/diff": "^3.0|^4.0",
         "symfony/console": "^4.4|^5.0",
         "symfony/dependency-injection": "^4.4|^5.0",
         "symfony/finder": "^4.4|^5.0",
@@ -38,7 +38,7 @@
         "friendsofphp/php-cs-fixer": "^2.16",
         "jetbrains/phpstorm-stubs": "^2019.2",
         "ocramius/package-versions": "^1.4|^1.5",
-        "phpunit/phpunit": "^8.4",
+        "phpunit/phpunit": "^8.4|^9.0",
         "symplify/changelog-linker": "^7.2",
         "symplify/easy-coding-standard": "^7.2",
         "symplify/monorepo-builder": "^7.2",