diff --git a/.arcconfig b/.arcconfig
index f0fa152929..88f04f72c5 100644
--- a/.arcconfig
+++ b/.arcconfig
@@ -1,4 +1,5 @@
 {
   "phabricator.uri": "https://secure.phabricator.com/",
-  "load": ["src/"]
+  "load": ["src/"],
+  "history.immutable": false
 }