diff --git a/composer.json b/composer.json
index 8f26ce0c..a1f5677b 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,7 @@
         "ext-iconv": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.8.36",
+        "phpunit/phpunit": "^5.7.27",
         "codacy/coverage": "^1.4.3"
     },
     "suggest": {