diff --git a/composer.json b/composer.json
index 25a41fe1..59d085bf 100644
--- a/composer.json
+++ b/composer.json
@@ -29,7 +29,7 @@
         "php": ">=5.3.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36"
+        "phpunit/phpunit": "^9.6 || ^8.5 || ^5.7 || ^4.8.36"
     },
     "suggest": {
         "ext-pcntl": "For signal handling support when using the StreamSelectLoop"