diff --git a/core/modules/user/user.admin.inc b/core/modules/user/user.admin.inc
index f7d4552..5c174e5 100644
--- a/core/modules/user/user.admin.inc
+++ b/core/modules/user/user.admin.inc
@@ -380,7 +380,7 @@ function user_admin_settings() {
     '#default_value' => variable_get('user_picture_default', ''),
     '#size' => 30,
     '#maxlength' => 255,
-    '#description' => t('URL of picture to display for users with no custom picture selected. Leave blank for none.'),
+    '#description' => t('Filename of the picture to display for users with no custom picture selected. It should be placed in the picture directory. Leave blank for none.'),
   );
   if (module_exists('image')) {
     $form['personalization']['pictures']['settings']['user_picture_style'] = array(
@@ -642,6 +642,18 @@ function user_admin_settings() {
 }
 
 /**
+ * Form validation handler for the user_admin_settings() form.
+ */
+function user_admin_settings_validate($form, &$form_state) {
+  if (!empty($form_state['values']['user_picture_default'])) {
+    $path = file_build_uri($form_state['values']['user_picture_path'] . '/' . $form_state['values']['user_picture_default']);
+    if (!file_valid_uri($path) || !file_exists(drupal_realpath($path))) {
+      form_set_error('user_picture_default', t('The default user image should be placed inside the %path directory.', array('%path' => $form_state['values']['user_picture_path'])));
+    }
+  }
+}
+
+/**
  * Menu callback: administer permissions.
  *
  * @ingroup forms
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 2dded35..1c6287e 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -1404,7 +1404,7 @@ function template_preprocess_user_picture(&$variables) {
       }
     }
     elseif (variable_get('user_picture_default', '')) {
-      $filepath = variable_get('user_picture_default', '');
+      $filepath = file_build_uri(variable_get('user_picture_path', '') . '/' . variable_get('user_picture_default', ''));
     }
     if (isset($filepath)) {
       $alt = t("@user's picture", array('@user' => format_username($account)));