diff --git a/src/applications/multimeter/controller/MultimeterSampleController.php b/src/applications/multimeter/controller/MultimeterSampleController.php
index 73c9ba530e..190a839f63 100644
--- a/src/applications/multimeter/controller/MultimeterSampleController.php
+++ b/src/applications/multimeter/controller/MultimeterSampleController.php
@@ -1,349 +1,350 @@
 <?php
 
 final class MultimeterSampleController extends MultimeterController {
 
   public function shouldAllowPublic() {
     return true;
   }
 
   public function handleRequest(AphrontRequest $request) {
     $viewer = $this->getViewer();
     $group_map = $this->getColumnMap();
 
     $group = explode('.', $request->getStr('group'));
     $group = array_intersect($group, array_keys($group_map));
     $group = array_fuse($group);
 
     if (empty($group['type'])) {
       $group['type'] = 'type';
     }
 
     $now = PhabricatorTime::getNow();
     $ago = ($now - phutil_units('24 hours in seconds'));
 
     $table = new MultimeterEvent();
     $conn = $table->establishConnection('r');
 
     $where = array();
     $where[] = qsprintf(
       $conn,
       'epoch >= %d AND epoch <= %d',
       $ago,
       $now);
 
     $with = array();
     foreach ($group_map as $key => $column) {
 
       // Don't let non-admins filter by viewers, this feels a little too
       // invasive of privacy.
       if ($key == 'viewer') {
         if (!$viewer->getIsAdmin()) {
           continue;
         }
       }
 
       $with[$key] = $request->getStrList($key);
       if ($with[$key]) {
         $where[] = qsprintf(
           $conn,
           '%T IN (%Ls)',
           $column,
           $with[$key]);
       }
     }
 
     $data = queryfx_all(
       $conn,
       'SELECT *,
           count(*) AS N,
           SUM(sampleRate * resourceCost) AS totalCost,
           SUM(sampleRate * resourceCost) / SUM(sampleRate) AS averageCost
         FROM %T
         WHERE %LA
         GROUP BY %LC
         ORDER BY totalCost DESC, MAX(id) DESC
         LIMIT 100',
       $table->getTableName(),
       $where,
       array_select_keys($group_map, $group));
 
     $this->loadDimensions($data);
     $phids = array();
     foreach ($data as $row) {
       $viewer_name = $this->getViewerDimension($row['eventViewerID'])
         ->getName();
       $viewer_phid = $this->getEventViewerPHID($viewer_name);
       if ($viewer_phid) {
         $phids[] = $viewer_phid;
       }
     }
     $handles = $viewer->loadHandles($phids);
 
     $rows = array();
     foreach ($data as $row) {
 
       if ($row['N'] == 1) {
         $events_col = $row['id'];
       } else {
         $events_col = $this->renderGroupingLink(
           $group,
           'id',
           pht('%s Event(s)', new PhutilNumber($row['N'])));
       }
 
       if (isset($group['request'])) {
         $request_col = $row['requestKey'];
         if (!$with['request']) {
           $request_col = $this->renderSelectionLink(
             'request',
             $row['requestKey'],
             $request_col);
         }
       } else {
         $request_col = $this->renderGroupingLink($group, 'request');
       }
 
       if (isset($group['viewer'])) {
         if ($viewer->getIsAdmin()) {
           $viewer_col = $this->getViewerDimension($row['eventViewerID'])
             ->getName();
 
           $viewer_phid = $this->getEventViewerPHID($viewer_col);
           if ($viewer_phid) {
             $viewer_col = $handles[$viewer_phid]->getName();
           }
 
           if (!$with['viewer']) {
             $viewer_col = $this->renderSelectionLink(
               'viewer',
               $row['eventViewerID'],
               $viewer_col);
           }
         } else {
           $viewer_col = phutil_tag('em', array(), pht('(Masked)'));
         }
       } else {
         $viewer_col = $this->renderGroupingLink($group, 'viewer');
       }
 
       if (isset($group['context'])) {
         $context_col = $this->getContextDimension($row['eventContextID'])
           ->getName();
         if (!$with['context']) {
           $context_col = $this->renderSelectionLink(
             'context',
             $row['eventContextID'],
             $context_col);
         }
       } else {
         $context_col = $this->renderGroupingLink($group, 'context');
       }
 
       if (isset($group['host'])) {
         $host_col = $this->getHostDimension($row['eventHostID'])
           ->getName();
         if (!$with['host']) {
           $host_col = $this->renderSelectionLink(
             'host',
             $row['eventHostID'],
             $host_col);
         }
       } else {
         $host_col = $this->renderGroupingLink($group, 'host');
       }
 
       if (isset($group['label'])) {
         $label_col = $this->getLabelDimension($row['eventLabelID'])
           ->getName();
         if (!$with['label']) {
           $label_col = $this->renderSelectionLink(
             'label',
             $row['eventLabelID'],
             $label_col);
         }
       } else {
         $label_col = $this->renderGroupingLink($group, 'label');
       }
 
       if ($with['type']) {
         $type_col = MultimeterEvent::getEventTypeName($row['eventType']);
       } else {
         $type_col = $this->renderSelectionLink(
           'type',
           $row['eventType'],
           MultimeterEvent::getEventTypeName($row['eventType']));
       }
 
       $rows[] = array(
         $events_col,
         $request_col,
         $viewer_col,
         $context_col,
         $host_col,
         $type_col,
         $label_col,
         MultimeterEvent::formatResourceCost(
           $viewer,
           $row['eventType'],
           $row['averageCost']),
         MultimeterEvent::formatResourceCost(
           $viewer,
           $row['eventType'],
           $row['totalCost']),
         ($row['N'] == 1)
           ? $row['sampleRate']
           : '-',
         phabricator_datetime($row['epoch'], $viewer),
       );
     }
 
     $table = id(new AphrontTableView($rows))
       ->setHeaders(
         array(
           pht('ID'),
           pht('Request'),
           pht('Viewer'),
           pht('Context'),
           pht('Host'),
           pht('Type'),
           pht('Label'),
           pht('Avg'),
           pht('Cost'),
           pht('Rate'),
           pht('Epoch'),
         ))
       ->setColumnClasses(
         array(
           null,
           null,
           null,
           null,
           null,
           null,
           'wide',
           'n',
           'n',
           'n',
           null,
         ));
 
     $box = id(new PHUIObjectBoxView())
       ->setHeaderText(pht('Samples'))
       ->setBackground(PHUIObjectBoxView::BLUE_PROPERTY)
       ->setTable($table);
 
     $crumbs = $this->buildApplicationCrumbs();
     $crumbs->addTextCrumb(
       pht('Samples'),
       $this->getGroupURI(array(), true));
     $crumbs->setBorder(true);
 
     $crumb_map = array(
       'host' => pht('By Host'),
       'context' => pht('By Context'),
       'viewer' => pht('By Viewer'),
       'request' => pht('By Request'),
       'label' => pht('By Label'),
       'id' => pht('By ID'),
     );
 
     $parts = array();
     foreach ($group as $item) {
       if ($item == 'type') {
         continue;
       }
       $parts[$item] = $item;
       $crumbs->addTextCrumb(
         idx($crumb_map, $item, $item),
         $this->getGroupURI($parts, true));
     }
 
     $header = id(new PHUIHeaderView())
       ->setHeader(
         pht(
           'Samples (%s - %s)',
           phabricator_datetime($ago, $viewer),
           phabricator_datetime($now, $viewer)))
       ->setHeaderIcon('fa-motorcycle');
 
     $view = id(new PHUITwoColumnView())
       ->setHeader($header)
       ->setFooter($box);
 
     return $this->newPage()
       ->setTitle(pht('Samples'))
       ->setCrumbs($crumbs)
       ->appendChild($view);
 
   }
 
   private function renderGroupingLink(array $group, $key, $name = null) {
     $group[] = $key;
     $uri = $this->getGroupURI($group);
 
     if ($name === null) {
       $name = pht('(All)');
     }
 
     return phutil_tag(
       'a',
       array(
         'href' => $uri,
         'style' => 'font-weight: bold',
       ),
       $name);
   }
 
   private function getGroupURI(array $group, $wipe = false) {
     unset($group['type']);
     $uri = clone $this->getRequest()->getRequestURI();
 
     $group = implode('.', $group);
     if (!strlen($group)) {
-      $group = null;
+      $uri->removeQueryParam('group');
+    } else {
+      $uri->replaceQueryParam('group', $group);
     }
-    $uri->replaceQueryParam('group', $group);
 
     if ($wipe) {
       foreach ($this->getColumnMap() as $key => $column) {
         $uri->removeQueryParam($key);
       }
     }
 
     return $uri;
   }
 
   private function renderSelectionLink($key, $value, $link_text) {
     $value = (array)$value;
 
     $uri = clone $this->getRequest()->getRequestURI();
     $uri->replaceQueryParam($key, implode(',', $value));
 
     return phutil_tag(
       'a',
       array(
         'href' => $uri,
       ),
       $link_text);
   }
 
   private function getColumnMap() {
     return array(
       'type' => 'eventType',
       'host' => 'eventHostID',
       'context' => 'eventContextID',
       'viewer' => 'eventViewerID',
       'request' => 'requestKey',
       'label' => 'eventLabelID',
       'id' => 'id',
     );
   }
 
   private function getEventViewerPHID($viewer_name) {
     if (!strncmp($viewer_name, 'user.', 5)) {
       return substr($viewer_name, 5);
     }
     return null;
   }
 
 }