diff --git a/.arcconfig b/.arcconfig
index 66841c44..513222b3 100644
--- a/.arcconfig
+++ b/.arcconfig
@@ -1,6 +1,7 @@
 {
   "phabricator.uri": "https://secure.phabricator.com/",
   "load": [
     "src/"
-  ]
+  ],
+  "history.immutable": false
 }