diff --git a/composer.json b/composer.json
index 46c16323..0728e762 100644
--- a/composer.json
+++ b/composer.json
@@ -29,7 +29,11 @@
     "require-dev": {
         "phpunit/phpunit": "^5.7"
     },
-    "extra": [],
+    "extra": {
+      "branch-alias": {
+        "dev-master": "4.1.x-dev"
+      }
+    },
     "autoload": {
         "psr-4": {
             "SilverStripe\\Reports\\": "code/",