diff --git a/src/applications/people/controller/PhabricatorPeopleController.php b/src/applications/people/controller/PhabricatorPeopleController.php
--- a/src/applications/people/controller/PhabricatorPeopleController.php
+++ b/src/applications/people/controller/PhabricatorPeopleController.php
@@ -16,7 +16,9 @@
       if ($name) {
         $nav->setBaseURI(new PhutilURI('/p/'));
         $nav->addFilter("{$name}/", $name);
-        $nav->addFilter("{$name}/calendar/", pht('Calendar'));
+        if (id(new PhabricatorCalendarApplication())->isInstalled()) {
+          $nav->addFilter("{$name}/calendar/", pht('Calendar'));
+        }
       }
     }