diff --git a/src/applications/calendar/editor/PhabricatorCalendarEventEditEngine.php b/src/applications/calendar/editor/PhabricatorCalendarEventEditEngine.php
--- a/src/applications/calendar/editor/PhabricatorCalendarEventEditEngine.php
+++ b/src/applications/calendar/editor/PhabricatorCalendarEventEditEngine.php
@@ -155,13 +155,6 @@
     }
 
     if ($this->getIsCreate() || $object->getIsRecurring()) {
-      $until_datetime = $object->newUntilDateTime();
-      if ($until_datetime) {
-        $until_epoch = $until_datetime->getEpoch();
-      } else {
-        $until_epoch = null;
-      }
-
       $fields[] = id(new PhabricatorEpochEditField())
         ->setAllowNull(true)
         ->setKey('until')
@@ -171,7 +164,7 @@
         ->setDescription(pht('Last instance of the event.'))
         ->setConduitDescription(pht('Change when the event repeats until.'))
         ->setConduitTypeDescription(pht('New final event time.'))
-        ->setValue($until_epoch);
+        ->setValue($object->getUntilDateTimeEpoch());
     }
 
     $fields[] = id(new PhabricatorBoolEditField())
diff --git a/src/applications/calendar/editor/PhabricatorCalendarEventEditor.php b/src/applications/calendar/editor/PhabricatorCalendarEventEditor.php
--- a/src/applications/calendar/editor/PhabricatorCalendarEventEditor.php
+++ b/src/applications/calendar/editor/PhabricatorCalendarEventEditor.php
@@ -139,7 +139,7 @@
           WHERE phid IN (%Ls) AND availabilityCacheTTL >= %d',
         $user->getTableName(),
         $phids,
-        $object->getDateFromForCache());
+        $object->getStartDateTimeEpochForCache());
     }
 
     return $xactions;
@@ -159,9 +159,9 @@
     $recurrence_end_xaction =
       PhabricatorCalendarEventUntilDateTransaction::TRANSACTIONTYPE;
 
-    $start_date = $object->getDateFrom();
-    $end_date = $object->getDateTo();
-    $recurrence_end = $object->getRecurrenceEndDate();
+    $start_date = $object->getStartDateTimeEpoch();
+    $end_date = $object->getEndDateTimeEpoch();
+    $recurrence_end = $object->getUntilDateTimeEpoch();
     $is_recurring = $object->getIsRecurring();
 
     $errors = array();
diff --git a/src/applications/calendar/storage/PhabricatorCalendarEvent.php b/src/applications/calendar/storage/PhabricatorCalendarEvent.php
--- a/src/applications/calendar/storage/PhabricatorCalendarEvent.php
+++ b/src/applications/calendar/storage/PhabricatorCalendarEvent.php
@@ -184,7 +184,7 @@
       ->setDescription($parent->getDescription());
 
     $sequence = $this->getSequenceIndex();
-    $duration = $this->getDuration();
+    $duration = $parent->getDuration();
     $epochs = $parent->getSequenceIndexEpochs($actor, $sequence, $duration);
 
     $this
@@ -277,7 +277,7 @@
   }
 
   public function getDuration() {
-    return $this->getDateTo() - $this->getDateFrom();
+    return ($this->getEndDateTimeEpoch() - $this->getStartDateTimeEpoch());
   }
 
   public function getDateEpochForTimezone(
@@ -366,7 +366,7 @@
    *
    * @return int Event start date for availability caches.
    */
-  public function getDateFromForCache() {
+  public function getStartDateTimeEpochForCache() {
     $epoch = $this->getStartDateTimeEpoch();
     $window = phutil_units('15 minutes in seconds');
     return ($epoch - $window);
@@ -794,6 +794,16 @@
     return $this->newDateTimeFromEpoch($epoch);
   }
 
+  public function getUntilDateTimeEpoch() {
+    $datetime = $this->newUntilDateTime();
+
+    if (!$datetime) {
+      return null;
+    }
+
+    return $datetime->getEpoch();
+  }
+
   public function newDuration() {
     return id(new PhutilCalendarDuration())
       ->setSeconds($this->getDuration());
diff --git a/src/applications/calendar/xaction/PhabricatorCalendarEventEndDateTransaction.php b/src/applications/calendar/xaction/PhabricatorCalendarEventEndDateTransaction.php
--- a/src/applications/calendar/xaction/PhabricatorCalendarEventEndDateTransaction.php
+++ b/src/applications/calendar/xaction/PhabricatorCalendarEventEndDateTransaction.php
@@ -6,7 +6,8 @@
   const TRANSACTIONTYPE = 'calendar.enddate';
 
   public function generateOldValue($object) {
-    return $object->getDateTo();
+    // TODO: Upgrade this.
+    return $object->getEndDateTimeEpoch();
   }
 
   public function applyInternalEffects($object, $value) {
diff --git a/src/applications/calendar/xaction/PhabricatorCalendarEventStartDateTransaction.php b/src/applications/calendar/xaction/PhabricatorCalendarEventStartDateTransaction.php
--- a/src/applications/calendar/xaction/PhabricatorCalendarEventStartDateTransaction.php
+++ b/src/applications/calendar/xaction/PhabricatorCalendarEventStartDateTransaction.php
@@ -6,7 +6,8 @@
   const TRANSACTIONTYPE = 'calendar.startdate';
 
   public function generateOldValue($object) {
-    return $object->getDateFrom();
+    // TODO: Upgrade this.
+    return $object->getStartDateTimeEpoch();
   }
 
   public function applyInternalEffects($object, $value) {
diff --git a/src/applications/calendar/xaction/PhabricatorCalendarEventUntilDateTransaction.php b/src/applications/calendar/xaction/PhabricatorCalendarEventUntilDateTransaction.php
--- a/src/applications/calendar/xaction/PhabricatorCalendarEventUntilDateTransaction.php
+++ b/src/applications/calendar/xaction/PhabricatorCalendarEventUntilDateTransaction.php
@@ -6,7 +6,8 @@
   const TRANSACTIONTYPE = 'calendar.recurrenceenddate';
 
   public function generateOldValue($object) {
-    return $object->getRecurrenceEndDate();
+    // TODO: Upgrade this.
+    return $object->getUntilDateTimeEpoch();
   }
 
   public function applyInternalEffects($object, $value) {
diff --git a/src/applications/people/query/PhabricatorPeopleQuery.php b/src/applications/people/query/PhabricatorPeopleQuery.php
--- a/src/applications/people/query/PhabricatorPeopleQuery.php
+++ b/src/applications/people/query/PhabricatorPeopleQuery.php
@@ -431,7 +431,7 @@
         // because of an event, we check again for events after that one ends.
         while (true) {
           foreach ($events as $event) {
-            $from = $event->getDateFromForCache();
+            $from = $event->getStartDateTimeEpochForCache();
             $to = $event->getEndDateTimeEpoch();
             if (($from <= $cursor) && ($to > $cursor)) {
               $cursor = $to;