diff --git a/composer.json b/composer.json
index 7adca7b..d6da56a 100644
--- a/composer.json
+++ b/composer.json
@@ -16,11 +16,7 @@
     "minimum-stability": "dev",
     "require":
     {
-        "silverstripe/cms": "^4"
-    },
-    "require-dev":
-    {
-        "phpunit/phpunit": "^5.7"
+        "silverstripe/cms": "*"
     },
     "extra":
     {