diff --git a/composer.json b/composer.json
index dcef64f7..52cc7a3f 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,6 @@
     }
   },
   "require-dev": {
-    "phpunit/phpunit": "^5.7",
-    "symfony/var-dumper": "^3.4"
+    "phpunit/phpunit": "<8"
   }
 }