diff --git a/core/lib/Drupal/Component/Annotation/Plugin.php b/core/lib/Drupal/Component/Annotation/Plugin.php
index 790440d1129287dcdcdd1f615bd874f93dedb480..504ff401d1aa7653db23ddc7d65e4ca495ac2d1c 100644
--- a/core/lib/Drupal/Component/Annotation/Plugin.php
+++ b/core/lib/Drupal/Component/Annotation/Plugin.php
@@ -39,7 +39,7 @@ public function __construct($values) {
       return $value !== NULL;
     });
     $parsed_values = $this->parse($values);
-    $this->definition = NestedArray::mergeDeep($defaults, $parsed_values);
+    $this->definition = NestedArray::mergeDeepArray([$defaults, $parsed_values], TRUE);
   }
 
   /**
diff --git a/core/tests/Drupal/Tests/Component/Annotation/PluginTest.php b/core/tests/Drupal/Tests/Component/Annotation/PluginTest.php
index d942764005faefbc1d6aa4fc4d332d22f99c25f1..554ed8dbeccd4ee868cc04c51b5e89d2621b2ae8 100644
--- a/core/tests/Drupal/Tests/Component/Annotation/PluginTest.php
+++ b/core/tests/Drupal/Tests/Component/Annotation/PluginTest.php
@@ -20,6 +20,7 @@ public function testGet() {
     // Assert all values are accepted through constructor and default value is
     // used for non existent but defined property.
     $plugin = new PluginStub([
+      1 => 'oak',
       'foo' => 'bar',
       'biz' => [
         'baz' => 'boom',
@@ -32,6 +33,7 @@ public function testGet() {
       // This property wasn't in our definition but is defined as a property on
       // our plugin class.
       'defaultProperty' => 'testvalue',
+      1 => 'oak',
       'foo' => 'bar',
       'biz' => [
         'baz' => 'boom',