diff --git a/.arcconfig b/.arcconfig
--- a/.arcconfig
+++ b/.arcconfig
@@ -1,4 +1,7 @@
 {
-  "project_id" : "lnt",
-  "conduit_uri" : "https://reviews.llvm.org/"
+  "phabricator_uri" : "https://reviews.llvm.org/",
+  "repository.callsign" : "LNT",
+  "conduit_uri" : "https://reviews.llvm.org/",
+  "base": "git:HEAD^",
+  "arc.land.onto.default": "main"
 }