diff --git a/includes/form.inc b/includes/form.inc
index f1691ad..e4bc620 100644
--- a/includes/form.inc
+++ b/includes/form.inc
@@ -3979,7 +3979,12 @@ function form_process_autocomplete($element) {
     // browser interpreting the path plus search string as an actual file.
     $current_clean_url = isset($GLOBALS['conf']['clean_url']) ? $GLOBALS['conf']['clean_url'] : NULL;
     $GLOBALS['conf']['clean_url'] = 0;
-    $element['#autocomplete_input']['#url_value'] = url($element['#autocomplete_path'], array('absolute' => TRUE));
+    // Force the script path to 'index.php', in case the server is not
+    // configured to find it automatically. Normally it is the responsibility
+    // of the site to do this themselves using hook_url_outbound_alter() (see
+    // url()) but since this code is forcing non-clean URLs on sites that don't
+    // normally use them, it is done here instead.
+    $element['#autocomplete_input']['#url_value'] = url($element['#autocomplete_path'], array('absolute' => TRUE, 'script' => 'index.php'));
     $GLOBALS['conf']['clean_url'] = $current_clean_url;
   }
   return $element;
diff --git a/modules/profile/profile.test b/modules/profile/profile.test
index 6cb0739..1892471 100644
--- a/modules/profile/profile.test
+++ b/modules/profile/profile.test
@@ -342,7 +342,7 @@ class ProfileTestAutocomplete extends ProfileTestCase {
     // Autocomplete always uses non-clean URLs.
     $current_clean_url = isset($GLOBALS['conf']['clean_url']) ? $GLOBALS['conf']['clean_url'] : NULL;
     $GLOBALS['conf']['clean_url'] = 0;
-    $autocomplete_url = url('profile/autocomplete/' . $field['fid'], array('absolute' => TRUE));
+    $autocomplete_url = url('profile/autocomplete/' . $field['fid'], array('absolute' => TRUE, 'script' => 'index.php'));
     $GLOBALS['conf']['clean_url'] = $current_clean_url;
     $autocomplete_id = drupal_html_id('edit-' . $field['form_name'] . '-autocomplete');
     $autocomplete_html = '<input type="hidden" id="' . $autocomplete_id . '" value="' . $autocomplete_url . '" disabled="disabled" class="autocomplete" />';