core/includes/pager.inc | 27 +++++++++++++++++----------
 core/includes/theme.inc |  2 +-
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/core/includes/pager.inc b/core/includes/pager.inc
index 47bf398..9904409 100644
--- a/core/includes/pager.inc
+++ b/core/includes/pager.inc
@@ -164,17 +164,24 @@ function pager_get_query_parameters() {
  *
  * @param array $variables
  *   An associative array containing:
- *   - tags: An array of labels for the controls in the pager.
- *   - element: An optional integer to distinguish between multiple pagers on
- *     one page.
- *   - parameters: An associative array of query string parameters to append to
- *     the pager links.
- *   - quantity: The number of pages in the list.
+ *   - pager: A render element containing:
+ *     - #tags: An array of labels for the controls in the pager.
+ *     - #element: An optional integer to distinguish between multiple pagers on
+ *       one page.
+ *     - #parameters: An associative array of query string parameters to append to
+ *       the pager links.
+ *     - #quantity: The number of pages in the list.
+ *
+ * @throws \RuntimeException
+ *   Whenever using #theme => pager instead of #type => pager.
  */
 function template_preprocess_pager(&$variables) {
-  $element = $variables['element'];
-  $parameters = $variables['parameters'];
-  $quantity = $variables['quantity'];
+  if (!isset($variables['pager']['#type'])) {
+    throw new \RuntimeException("You must use '#type' => 'pager', not '#theme' => 'pager'.");
+  }
+  $element = $variables['pager']['#element'];
+  $parameters = $variables['pager']['#parameters'];
+  $quantity = $variables['pager']['#quantity'];
   global $pager_page_array, $pager_total;
 
   // Nothing to do if there is only one page.
@@ -182,7 +189,7 @@ function template_preprocess_pager(&$variables) {
     return;
   }
 
-  $tags = $variables['tags'];
+  $tags = $variables['pager']['#tags'];
 
   // Calculate various markers within this pager piece:
   // Middle is used to "center" pages around the current page.
diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index b6078ed..1ecd5e8 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1861,7 +1861,7 @@ function drupal_common_theme() {
     ),
     // From pager.inc.
     'pager' => array(
-      'variables' => array('tags' => array(), 'element' => 0, 'parameters' => array(), 'quantity' => 9),
+      'render element' => 'pager',
     ),
     // From menu.inc.
     'menu' => array(