diff --git a/composer.json b/composer.json
index d6b413c..a3a2d60 100644
--- a/composer.json
+++ b/composer.json
@@ -7,7 +7,7 @@
     "hsldymq/whisper": "~0.3.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "~6.4.0"
+    "phpunit/phpunit": "~6.4"
   },
   "autoload": {
     "psr-4": {