diff --git a/src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php b/src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php
--- a/src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php
+++ b/src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php
@@ -141,7 +141,9 @@
       return array();
     }
 
-    $tokens = preg_split('/[\s\[\]-]+/u', $string);
+    // NOTE: Splitting on "(" and ")" is important for milestones.
+
+    $tokens = preg_split('/[\s\[\]\(\)-]+/u', $string);
     $tokens = array_unique($tokens);
 
     // Make sure we don't return the empty token, as this will boil down to a
diff --git a/src/applications/typeahead/datasource/__tests__/PhabricatorTypeaheadDatasourceTestCase.php b/src/applications/typeahead/datasource/__tests__/PhabricatorTypeaheadDatasourceTestCase.php
--- a/src/applications/typeahead/datasource/__tests__/PhabricatorTypeaheadDatasourceTestCase.php
+++ b/src/applications/typeahead/datasource/__tests__/PhabricatorTypeaheadDatasourceTestCase.php
@@ -27,6 +27,18 @@
     $this->assertTokenization(
       '[[ brackets ]] [-] ]-[ tie-fighters',
       array('brackets', 'tie', 'fighters'));
+
+    $this->assertTokenization(
+      'viewer()',
+      array('viewer'));
+
+    $this->assertTokenization(
+      'Work (Done)',
+      array('work', 'done'));
+
+    $this->assertTokenization(
+      'A (B C D)',
+      array('a', 'b', 'c', 'd'));
   }
 
   private function assertTokenization($input, $expect) {