diff --git a/src/DiffLayoutManager.php b/src/DiffLayoutManager.php
index befb7a4..35c3431 100644
--- a/src/DiffLayoutManager.php
+++ b/src/DiffLayoutManager.php
@@ -92,7 +92,7 @@ class DiffLayoutManager extends DefaultPluginManager {
    *   The id of the default plugin.
    */
   public function getDefaultLayout() {
-    $plugins = $this->getPluginOptions();
-    return reset(array_keys($plugins));
+    $plugins = array_keys($this->getPluginOptions());
+    return reset($plugins);
   }
 }