diff --git a/src/applications/phrequent/query/PhrequentSearchEngine.php b/src/applications/phrequent/query/PhrequentSearchEngine.php
index c45fd4a290..0569c93822 100644
--- a/src/applications/phrequent/query/PhrequentSearchEngine.php
+++ b/src/applications/phrequent/query/PhrequentSearchEngine.php
@@ -1,203 +1,201 @@
 <?php
 
 final class PhrequentSearchEngine extends PhabricatorApplicationSearchEngine {
 
   public function getResultTypeDescription() {
     return pht('Phrequent Time');
   }
 
   public function getApplicationClassName() {
     return 'PhabricatorPhrequentApplication';
   }
 
   public function getPageSize(PhabricatorSavedQuery $saved) {
     return $saved->getParameter('limit', 1000);
   }
 
   public function buildSavedQueryFromRequest(AphrontRequest $request) {
     $saved = new PhabricatorSavedQuery();
 
     $saved->setParameter(
       'userPHIDs',
       $this->readUsersFromRequest($request, 'users'));
 
     $saved->setParameter('ended', $request->getStr('ended'));
 
     $saved->setParameter('order', $request->getStr('order'));
 
     return $saved;
   }
 
   public function buildQueryFromSavedQuery(PhabricatorSavedQuery $saved) {
-    $query = id(new PhrequentUserTimeQuery());
+    $query = id(new PhrequentUserTimeQuery())
+      ->needPreemptingEvents(true);
 
     $user_phids = $saved->getParameter('userPHIDs');
     if ($user_phids) {
       $query->withUserPHIDs($user_phids);
     }
 
     $ended = $saved->getParameter('ended');
     if ($ended != null) {
       $query->withEnded($ended);
     }
 
     $order = $saved->getParameter('order');
     if ($order != null) {
       $query->setOrder($order);
     }
 
     return $query;
   }
 
   public function buildSearchForm(
     AphrontFormView $form,
     PhabricatorSavedQuery $saved_query) {
 
     $user_phids = $saved_query->getParameter('userPHIDs', array());
     $ended = $saved_query->getParameter(
       'ended', PhrequentUserTimeQuery::ENDED_ALL);
     $order = $saved_query->getParameter(
       'order', PhrequentUserTimeQuery::ORDER_ENDED_DESC);
 
     $phids = array_merge($user_phids);
     $handles = id(new PhabricatorHandleQuery())
       ->setViewer($this->requireViewer())
       ->withPHIDs($phids)
       ->execute();
 
     $form
       ->appendChild(
         id(new AphrontFormTokenizerControl())
           ->setDatasource(new PhabricatorPeopleDatasource())
           ->setName('users')
           ->setLabel(pht('Users'))
           ->setValue($handles))
       ->appendChild(
         id(new AphrontFormSelectControl())
           ->setLabel(pht('Ended'))
           ->setName('ended')
           ->setValue($ended)
           ->setOptions(PhrequentUserTimeQuery::getEndedSearchOptions()))
       ->appendChild(
         id(new AphrontFormSelectControl())
           ->setLabel(pht('Order'))
           ->setName('order')
           ->setValue($order)
           ->setOptions(PhrequentUserTimeQuery::getOrderSearchOptions()));
   }
 
   protected function getURI($path) {
     return '/phrequent/'.$path;
   }
 
   public function getBuiltinQueryNames() {
     return array(
       'tracking' => pht('Currently Tracking'),
       'all' => pht('All Tracked'),
     );
   }
 
   public function buildSavedQueryFromBuiltin($query_key) {
     $query = $this->newSavedQuery();
     $query->setQueryKey($query_key);
 
     switch ($query_key) {
       case 'all':
         return $query
           ->setParameter('order', PhrequentUserTimeQuery::ORDER_ENDED_DESC);
       case 'tracking':
         return $query
           ->setParameter('ended', PhrequentUserTimeQuery::ENDED_NO)
           ->setParameter('order', PhrequentUserTimeQuery::ORDER_ENDED_DESC);
     }
 
     return parent::buildSavedQueryFromBuiltin($query_key);
   }
 
   protected function getRequiredHandlePHIDsForResultList(
     array $usertimes,
     PhabricatorSavedQuery $query) {
     return array_mergev(
       array(
         mpull($usertimes, 'getUserPHID'),
         mpull($usertimes, 'getObjectPHID'),
       ));
   }
 
   protected function renderResultList(
     array $usertimes,
     PhabricatorSavedQuery $query,
     array $handles) {
     assert_instances_of($usertimes, 'PhrequentUserTime');
     $viewer = $this->requireViewer();
 
     $view = id(new PHUIObjectItemListView())
       ->setUser($viewer);
 
     foreach ($usertimes as $usertime) {
       $item = new PHUIObjectItemView();
-
       if ($usertime->getObjectPHID() === null) {
         $item->setHeader($usertime->getNote());
       } else {
         $obj = $handles[$usertime->getObjectPHID()];
         $item->setHeader($obj->getLinkName());
         $item->setHref($obj->getURI());
       }
       $item->setObject($usertime);
 
       $item->addByline(
         pht(
           'Tracked: %s',
           $handles[$usertime->getUserPHID()]->renderLink()));
 
       $started_date = phabricator_date($usertime->getDateStarted(), $viewer);
       $item->addIcon('none', $started_date);
 
-      if ($usertime->getDateEnded() !== null) {
-        $time_spent = $usertime->getDateEnded() - $usertime->getDateStarted();
-        $time_ended = phabricator_datetime($usertime->getDateEnded(), $viewer);
-      } else {
-        $time_spent = time() - $usertime->getDateStarted();
-      }
+      $block = new PhrequentTimeBlock(array($usertime));
+      $time_spent = $block->getTimeSpentOnObject(
+        $usertime->getObjectPHID(),
+        PhabricatorTime::getNow());
 
       $time_spent = $time_spent == 0 ? 'none' :
         phutil_format_relative_time_detailed($time_spent);
 
       if ($usertime->getDateEnded() !== null) {
         $item->addAttribute(
           pht(
             'Tracked %s',
             $time_spent));
         $item->addAttribute(
           pht(
             'Ended on %s',
-            $time_ended));
+            phabricator_datetime($usertime->getDateEnded(), $viewer)));
       } else {
         $item->addAttribute(
           pht(
             'Tracked %s so far',
             $time_spent));
         if ($usertime->getObjectPHID() !== null &&
             $usertime->getUserPHID() === $viewer->getPHID()) {
           $item->addAction(
             id(new PHUIListItemView())
               ->setIcon('fa-stop')
               ->addSigil('phrequent-stop-tracking')
               ->setWorkflow(true)
               ->setRenderNameAsTooltip(true)
               ->setName(pht('Stop'))
               ->setHref(
                 '/phrequent/track/stop/'.
                 $usertime->getObjectPHID().'/'));
         }
         $item->setBarColor('green');
       }
 
       $view->addItem($item);
     }
 
     return $view;
   }
 
 }
diff --git a/src/applications/phrequent/query/PhrequentUserTimeQuery.php b/src/applications/phrequent/query/PhrequentUserTimeQuery.php
index c173741c7a..2bb4674ddd 100644
--- a/src/applications/phrequent/query/PhrequentUserTimeQuery.php
+++ b/src/applications/phrequent/query/PhrequentUserTimeQuery.php
@@ -1,309 +1,330 @@
 <?php
 
 final class PhrequentUserTimeQuery
   extends PhabricatorCursorPagedPolicyAwareQuery {
 
   const ORDER_ID_ASC        = 0;
   const ORDER_ID_DESC       = 1;
   const ORDER_STARTED_ASC   = 2;
   const ORDER_STARTED_DESC  = 3;
   const ORDER_ENDED_ASC     = 4;
   const ORDER_ENDED_DESC    = 5;
   const ORDER_DURATION_ASC  = 6;
   const ORDER_DURATION_DESC = 7;
 
   const ENDED_YES = 0;
   const ENDED_NO  = 1;
   const ENDED_ALL = 2;
 
   private $userPHIDs;
   private $objectPHIDs;
   private $order = self::ORDER_ID_ASC;
   private $ended = self::ENDED_ALL;
 
   private $needPreemptingEvents;
 
   public function withUserPHIDs($user_phids) {
     $this->userPHIDs = $user_phids;
     return $this;
   }
 
   public function withObjectPHIDs($object_phids) {
     $this->objectPHIDs = $object_phids;
     return $this;
   }
 
   public function withEnded($ended) {
     $this->ended = $ended;
     return $this;
   }
 
   public function setOrder($order) {
     $this->order = $order;
     return $this;
   }
 
   public function needPreemptingEvents($need_events) {
     $this->needPreemptingEvents = $need_events;
     return $this;
   }
 
   private function buildWhereClause(AphrontDatabaseConnection $conn) {
     $where = array();
 
     if ($this->userPHIDs) {
       $where[] = qsprintf(
         $conn,
         'userPHID IN (%Ls)',
         $this->userPHIDs);
     }
 
     if ($this->objectPHIDs) {
       $where[] = qsprintf(
         $conn,
         'objectPHID IN (%Ls)',
         $this->objectPHIDs);
     }
 
     switch ($this->ended) {
       case self::ENDED_ALL:
         break;
       case self::ENDED_YES:
         $where[] = qsprintf(
           $conn,
           'dateEnded IS NOT NULL');
         break;
       case self::ENDED_NO:
         $where[] = qsprintf(
           $conn,
           'dateEnded IS NULL');
         break;
       default:
         throw new Exception("Unknown ended '{$this->ended}'!");
     }
 
     $where[] = $this->buildPagingClause($conn);
 
     return $this->formatWhereClause($where);
   }
 
   protected function getPagingColumn() {
     switch ($this->order) {
       case self::ORDER_ID_ASC:
       case self::ORDER_ID_DESC:
         return 'id';
       case self::ORDER_STARTED_ASC:
       case self::ORDER_STARTED_DESC:
         return 'dateStarted';
       case self::ORDER_ENDED_ASC:
       case self::ORDER_ENDED_DESC:
         return 'dateEnded';
       case self::ORDER_DURATION_ASC:
       case self::ORDER_DURATION_DESC:
         return 'COALESCE(dateEnded, UNIX_TIMESTAMP()) - dateStarted';
       default:
         throw new Exception("Unknown order '{$this->order}'!");
     }
   }
 
   protected function getPagingValue($result) {
     switch ($this->order) {
       case self::ORDER_ID_ASC:
       case self::ORDER_ID_DESC:
         return $result->getID();
       case self::ORDER_STARTED_ASC:
       case self::ORDER_STARTED_DESC:
         return $result->getDateStarted();
       case self::ORDER_ENDED_ASC:
       case self::ORDER_ENDED_DESC:
         return $result->getDateEnded();
       case self::ORDER_DURATION_ASC:
       case self::ORDER_DURATION_DESC:
         return ($result->getDateEnded() || time()) - $result->getDateStarted();
       default:
         throw new Exception("Unknown order '{$this->order}'!");
     }
   }
 
   protected function getReversePaging() {
     switch ($this->order) {
       case self::ORDER_ID_ASC:
       case self::ORDER_STARTED_ASC:
       case self::ORDER_ENDED_ASC:
       case self::ORDER_DURATION_ASC:
         return true;
       case self::ORDER_ID_DESC:
       case self::ORDER_STARTED_DESC:
       case self::ORDER_ENDED_DESC:
       case self::ORDER_DURATION_DESC:
         return false;
       default:
         throw new Exception("Unknown order '{$this->order}'!");
     }
   }
 
   protected function loadPage() {
     $usertime = new PhrequentUserTime();
     $conn = $usertime->establishConnection('r');
 
     $data = queryfx_all(
       $conn,
       'SELECT usertime.* FROM %T usertime %Q %Q %Q',
       $usertime->getTableName(),
       $this->buildWhereClause($conn),
       $this->buildOrderClause($conn),
       $this->buildLimitClause($conn));
 
     return $usertime->loadAllFromArray($data);
   }
 
   protected function didFilterPage(array $page) {
     if ($this->needPreemptingEvents) {
       $usertime = new PhrequentUserTime();
       $conn_r = $usertime->establishConnection('r');
 
       $preempt = array();
       foreach ($page as $event) {
         $preempt[] = qsprintf(
           $conn_r,
           '(userPHID = %s AND
             (dateStarted BETWEEN %d AND %d) AND
             (dateEnded IS NULL OR dateEnded > %d))',
           $event->getUserPHID(),
           $event->getDateStarted(),
           nonempty($event->getDateEnded(), PhabricatorTime::getNow()),
           $event->getDateStarted());
       }
 
       $preempting_events = queryfx_all(
         $conn_r,
         'SELECT * FROM %T WHERE %Q ORDER BY dateStarted ASC, id ASC',
         $usertime->getTableName(),
         implode(' OR ', $preempt));
       $preempting_events = $usertime->loadAllFromArray($preempting_events);
 
       $preempting_events = mgroup($preempting_events, 'getUserPHID');
 
       foreach ($page as $event) {
         $e_start = $event->getDateStarted();
         $e_end = $event->getDateEnded();
 
         $select = array();
         $user_events = idx($preempting_events, $event->getUserPHID(), array());
         foreach ($user_events as $u_event) {
           if ($u_event->getID() == $event->getID()) {
             // Don't allow an event to preempt itself.
             continue;
           }
 
           $u_start = $u_event->getDateStarted();
           $u_end = $u_event->getDateEnded();
 
-          if (($u_start >= $e_start) &&
-              ($u_end === null || $u_end > $e_start)) {
-            $select[] = $u_event;
+          if ($u_start < $e_start) {
+            // This event started before our event started, so it's not
+            // preempting us.
+            continue;
+          }
+
+          if ($u_start == $e_start) {
+            if ($u_event->getID() < $event->getID()) {
+              // This event started at the same time as our event started,
+              // but has a lower ID, so it's not preempting us.
+              continue;
+            }
+          }
+
+          if (($e_end !== null) && ($u_start > $e_end)) {
+            // Our event has ended, and this event started after it ended.
+            continue;
           }
+
+          if (($u_end !== null) && ($u_end < $e_start)) {
+            // This event ended before our event began.
+            continue;
+          }
+
+          $select[] = $u_event;
         }
 
         $event->attachPreemptingEvents($select);
       }
     }
 
     return $page;
   }
 
 /* -(  Helper Functions ) --------------------------------------------------- */
 
   public static function getEndedSearchOptions() {
     return array(
       self::ENDED_ALL => pht('All'),
       self::ENDED_NO  => pht('No'),
       self::ENDED_YES => pht('Yes'));
   }
 
   public static function getOrderSearchOptions() {
     return array(
       self::ORDER_STARTED_ASC   => pht('by furthest start date'),
       self::ORDER_STARTED_DESC  => pht('by nearest start date'),
       self::ORDER_ENDED_ASC     => pht('by furthest end date'),
       self::ORDER_ENDED_DESC    => pht('by nearest end date'),
       self::ORDER_DURATION_ASC  => pht('by smallest duration'),
       self::ORDER_DURATION_DESC => pht('by largest duration'));
   }
 
   public static function getUserTotalObjectsTracked(
     PhabricatorUser $user) {
 
     $usertime_dao = new PhrequentUserTime();
     $conn = $usertime_dao->establishConnection('r');
 
     $count = queryfx_one(
       $conn,
       'SELECT COUNT(usertime.id) N FROM %T usertime '.
       'WHERE usertime.userPHID = %s '.
       'AND usertime.dateEnded IS NULL',
       $usertime_dao->getTableName(),
       $user->getPHID());
     return $count['N'];
   }
 
   public static function isUserTrackingObject(
     PhabricatorUser $user,
     $phid) {
 
     $usertime_dao = new PhrequentUserTime();
     $conn = $usertime_dao->establishConnection('r');
 
     $count = queryfx_one(
       $conn,
       'SELECT COUNT(usertime.id) N FROM %T usertime '.
       'WHERE usertime.userPHID = %s '.
       'AND usertime.objectPHID = %s '.
       'AND usertime.dateEnded IS NULL',
       $usertime_dao->getTableName(),
       $user->getPHID(),
       $phid);
     return $count['N'] > 0;
   }
 
   public static function getUserTimeSpentOnObject(
     PhabricatorUser $user,
     $phid) {
 
     $usertime_dao = new PhrequentUserTime();
     $conn = $usertime_dao->establishConnection('r');
 
     // First calculate all the time spent where the
     // usertime blocks have ended.
     $sum_ended = queryfx_one(
       $conn,
       'SELECT SUM(usertime.dateEnded - usertime.dateStarted) N '.
       'FROM %T usertime '.
       'WHERE usertime.userPHID = %s '.
       'AND usertime.objectPHID = %s '.
       'AND usertime.dateEnded IS NOT NULL',
       $usertime_dao->getTableName(),
       $user->getPHID(),
       $phid);
 
     // Now calculate the time spent where the usertime
     // blocks have not yet ended.
     $sum_not_ended = queryfx_one(
       $conn,
       'SELECT SUM(UNIX_TIMESTAMP() - usertime.dateStarted) N '.
       'FROM %T usertime '.
       'WHERE usertime.userPHID = %s '.
       'AND usertime.objectPHID = %s '.
       'AND usertime.dateEnded IS NULL',
       $usertime_dao->getTableName(),
       $user->getPHID(),
       $phid);
 
     return $sum_ended['N'] + $sum_not_ended['N'];
   }
 
   public function getQueryApplicationClass() {
     return 'PhabricatorPhrequentApplication';
   }
 
 }