diff --git a/composer.json b/composer.json
index 742e520..c0a6ebc 100644
--- a/composer.json
+++ b/composer.json
@@ -29,7 +29,7 @@
         }
     },
     "require-dev": {
-        "phpunit/phpunit": "~8.0",
+        "phpunit/phpunit": "~7.0",
         "phpbench/phpbench": "^0.14.0"
     },
     "scripts": {