diff --git a/src/applications/diffusion/controller/history/DiffusionHistoryController.php b/src/applications/diffusion/controller/history/DiffusionHistoryController.php
index 8c2fa9ab52..de2ecba0a4 100644
--- a/src/applications/diffusion/controller/history/DiffusionHistoryController.php
+++ b/src/applications/diffusion/controller/history/DiffusionHistoryController.php
@@ -30,7 +30,7 @@ class DiffusionHistoryController extends DiffusionController {
     $history_query->setOffset($offset);
     $history_query->setLimit($page_size + 1);
 
-    if ($request->getStr('copies') !== 'true') {
+    if (!$request->getBool('copies')) {
       $history_query->needDirectChanges(true);
     }
 
@@ -68,14 +68,16 @@ class DiffusionHistoryController extends DiffusionController {
         'view'   => 'history',
       ));
 
-    if ($request->getStr('copies') === 'true') {
-      $button_uri = '?copies=false';
+    if ($request->getBool('copies')) {
       $button_title = 'Hide Copies/Branches';
     } else {
-      $button_uri = '?copies=true';
       $button_title = 'Show Copies/Branches';
     }
 
+    $button_uri = $request->getRequestURI()->alter(
+      'copies',
+      !$request->getBool('copies'));
+
     $button = phutil_render_tag(
       'a',
       array(
diff --git a/src/applications/diffusion/controller/history/__init__.php b/src/applications/diffusion/controller/history/__init__.php
index 02cc7325be..c8589c78e6 100644
--- a/src/applications/diffusion/controller/history/__init__.php
+++ b/src/applications/diffusion/controller/history/__init__.php
@@ -14,6 +14,7 @@ phutil_require_module('phabricator', 'view/control/pager');
 phutil_require_module('phabricator', 'view/layout/panel');
 
 phutil_require_module('phutil', 'markup');
+phutil_require_module('phutil', 'parser/uri');
 phutil_require_module('phutil', 'utils');