1 files changed, 1 insertions, 1 deletions
diff --git a/composer.json b/composer.json
index 2603aad..c782dbc 100644
--- a/composer.json
+++ b/composer.json
@@ -44,7 +44,7 @@
         }
     },
     "require-dev": {
-        "phpunit/phpunit" : "*"
+        "phpunit/phpunit" : "^6"
     },
     "config" : {
         "bin-dir" : "bin/"