diff --git a/composer.json b/composer.json
index cbc6a38..7ae425f 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
         "ext-tokenizer": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^6"
+        "phpunit/phpunit": "^6.5 || ^7.0"
     },
     "autoload": {
         "psr-4": {