diff --git a/core/modules/layout/layout.module b/core/modules/layout/layout.module
index 7d82798..64d7714 100644
--- a/core/modules/layout/layout.module
+++ b/core/modules/layout/layout.module
@@ -23,11 +23,13 @@ function layout_manager() {
 function layout_theme($existing, $type, $theme, $path) {
   $items = array();
   foreach (layout_manager()->getDefinitions() as $name => $layout) {
-    $items[$layout['theme']] = array(
-      'variables' => array('content' => NULL),
-      'path' => $layout['path'],
-      'template' => $layout['template'],
-    );
+    if (!empty($layout['theme'])) {
+      $items[$layout['theme']] = array(
+        'variables' => array('content' => NULL),
+        'path' => $layout['path'],
+        'template' => $layout['template'],
+      );
+    }
   }
   return $items;
 }