diff --git a/src/repository/api/ArcanistMercurialAPI.php b/src/repository/api/ArcanistMercurialAPI.php
index 0029c318..2d7484a8 100644
--- a/src/repository/api/ArcanistMercurialAPI.php
+++ b/src/repository/api/ArcanistMercurialAPI.php
@@ -917,7 +917,7 @@ final class ArcanistMercurialAPI extends ArcanistRepositoryAPI {
   }
 
   public function isHgSubversionRepo() {
-    return file_exists($this->getPath('.hg/svn'));
+    return file_exists($this->getPath('.hg/svn/rev_map'));
   }
 
   public function getSubversionInfo() {