diff --git a/src/repository/marker/ArcanistRepositoryMarkerQuery.php b/src/repository/marker/ArcanistRepositoryMarkerQuery.php
--- a/src/repository/marker/ArcanistRepositoryMarkerQuery.php
+++ b/src/repository/marker/ArcanistRepositoryMarkerQuery.php
@@ -64,8 +64,10 @@
       $marker->attachWorkingCopyStateRef($state_ref);
 
       $hash = $marker->getCommitHash();
-      $hash = $api->getDisplayHash($hash);
-      $marker->setDisplayHash($hash);
+      if ($hash !== null) {
+        $hash = $api->getDisplayHash($hash);
+        $marker->setDisplayHash($hash);
+      }
     }
 
     $types = $this->markerTypes;