diff --git a/src/applications/diffusion/controller/DiffusionRepositoryEditController.php b/src/applications/diffusion/controller/DiffusionRepositoryEditController.php
index af05f6719f..04946cdcdd 100644
--- a/src/applications/diffusion/controller/DiffusionRepositoryEditController.php
+++ b/src/applications/diffusion/controller/DiffusionRepositoryEditController.php
@@ -14,7 +14,7 @@ final class DiffusionRepositoryEditController
 
       $vcs = $request->getStr('vcs');
       $vcs_types = PhabricatorRepositoryType::getRepositoryTypeMap();
-      if (empty($vcs_types[$vcs])) {
+      if (!$vcs || empty($vcs_types[$vcs])) {
         return $this->buildVCSTypeResponse();
       }