1 files changed, 1 insertions, 1 deletions
diff --git a/composer.json b/composer.json
index 4c3b314..de7817d 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,7 @@
       "php": ">=5.6"
     },
     "require-dev": {
-        "phpunit/phpunit": "4.2.*",
+        "phpunit/phpunit": "~4.8.35 || ~5.7 || ~6.4",
         "squizlabs/php_codesniffer": "~1.5"
     }
 }