diff --git a/composer.json b/composer.json
index c67d35c3..9b63e789 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,7 @@
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^2.0",
-        "phpunit/phpunit": "^4.8.35 || ^6.0"
+        "phpunit/phpunit": "^4.8.35 || ^5.4.3 || ^6.0"
     },
     "autoload": {
         "psr-4": {