diff --git a/.arcconfig b/.arcconfig
new file mode 100644
--- /dev/null
+++ b/.arcconfig
@@ -0,0 +1,6 @@
+{
+    "conduit_uri": "https://phab.mercurial-scm.org/api",
+    "repository.callsign": "HG",
+    "arc.land.onto.default": "@",
+    "base": "hg:.^"
+}
diff --git a/tests/test-check-code.t b/tests/test-check-code.t
--- a/tests/test-check-code.t
+++ b/tests/test-check-code.t
@@ -36,6 +36,7 @@
 Prevent adding new files in the root directory accidentally.
 
   $ testrepohg files 'glob:*'
+  .arcconfig
   .editorconfig
   .hgignore
   .hgsigs