Index: hierarchical_select.js
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/hierarchical_select/hierarchical_select.js,v
retrieving revision 1.95
diff -u -F^f -r1.95 hierarchical_select.js
--- hierarchical_select.js	15 Aug 2009 10:44:59 -0000	1.95
+++ hierarchical_select.js	15 Aug 2009 13:14:19 -0000
@@ -501,11 +501,22 @@
       break;
   }
 
+  // Construct the URL the request should be made to. GET arguments may not be
+  // forgotten.
+  var url = Drupal.settings.HierarchicalSelect.basePath + Drupal.settings.HierarchicalSelect.settings[hsid]['path'];
+  var i = 0;
+  for (var key in Drupal.settings.HierarchicalSelect.getArguments) {
+    url += (i == 0) ? '?' : '&';
+    url += key;
+    url += '=';
+    url += Drupal.settings.HierarchicalSelect.getArguments[key];
+  }
+
   // Construct the object that contains the options for a callback to the
   // server. If a client-side cache is found however, it's possible that this
   // won't be used.
   var ajaxOptions = {
-    url:        Drupal.settings.HierarchicalSelect.basePath + Drupal.settings.HierarchicalSelect.settings[hsid]['path'],
+    url:        url,
     type:       'POST',
     dataType:   'json',
     data:       post,
Index: hierarchical_select.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/hierarchical_select/hierarchical_select.module,v
retrieving revision 1.169
diff -u -F^f -r1.169 hierarchical_select.module
--- hierarchical_select.module	15 Aug 2009 12:12:44 -0000	1.169
+++ hierarchical_select.module	15 Aug 2009 13:14:21 -0000
@@ -1316,7 +1316,12 @@ function _hierarchical_select_setup_js(&
   if (!$js_settings_added && isset($form_state)) {
     $url = base_path();
     $url .= variable_get('clean_url', 0) ? '' : 'index.php?q=';
-    _hierarchical_select_add_js_settings(array('HierarchicalSelect' => array('basePath' => $url)), $form_state);
+
+    $get_arguments = $_GET;
+    unset($get_arguments['q']);
+
+    _hierarchical_select_add_js_settings(array('HierarchicalSelect' => array('basePath' => $url, 'getArguments' => $get_arguments)), $form_state);
+
     $js_settings_added = TRUE;
   }