diff --git a/src/applications/calendar/query/PhabricatorCalendarEventSearchEngine.php b/src/applications/calendar/query/PhabricatorCalendarEventSearchEngine.php
--- a/src/applications/calendar/query/PhabricatorCalendarEventSearchEngine.php
+++ b/src/applications/calendar/query/PhabricatorCalendarEventSearchEngine.php
@@ -127,14 +127,14 @@
     }
 
     $invited_phids = $saved->getParameter('invitedPHIDs');
-    $invited_phids = $user_datasource->evaluateTokens($invited_phids);
     if ($invited_phids) {
+      $invited_phids = $user_datasource->evaluateTokens($invited_phids);
       $query->withInvitedPHIDs($invited_phids);
     }
 
     $creator_phids = $saved->getParameter('creatorPHIDs');
-    $creator_phids = $user_datasource->evaluateTokens($creator_phids);
     if ($creator_phids) {
+      $creator_phids = $user_datasource->evaluateTokens($creator_phids);
       $query->withCreatorPHIDs($creator_phids);
     }