diff --git a/core/modules/block/block.links.action.yml b/core/modules/block/block.links.action.yml
index 8c3c871..9b2a61e 100644
--- a/core/modules/block/block.links.action.yml
+++ b/core/modules/block/block.links.action.yml
@@ -4,3 +4,4 @@ block_admin_placement_action:
   appears_on:
     - block.admin_display
     - block.admin_display_theme
+  class: \Drupal\block\Plugin\Menu\LocalAction\BlockAddLocalAction
diff --git a/core/modules/block/src/Controller/BlockListController.php b/core/modules/block/src/Controller/BlockListController.php
index ee505d9..376b960 100644
--- a/core/modules/block/src/Controller/BlockListController.php
+++ b/core/modules/block/src/Controller/BlockListController.php
@@ -35,6 +35,9 @@ public function listing($theme = NULL, Request $request = NULL) {
   }
 
   public function placement($theme = NULL, Request $request = NULL) {
+    if (empty($theme)) {
+      $theme = $request->query->get('theme');
+    }
     $theme = $theme ?: $this->config('system.theme')->get('default');
     $block_manager = \Drupal::service('plugin.manager.block');
 
diff --git a/core/modules/block/src/Plugin/Menu/LocalAction/BlockAddLocalAction.php b/core/modules/block/src/Plugin/Menu/LocalAction/BlockAddLocalAction.php
new file mode 100644
index 0000000..93eaadd
--- /dev/null
+++ b/core/modules/block/src/Plugin/Menu/LocalAction/BlockAddLocalAction.php
@@ -0,0 +1,32 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\block\Plugin\Menu\LocalAction\BlockAddLocalAction.
+ */
+
+namespace Drupal\block\Plugin\Menu\LocalAction;
+
+use Drupal\Core\Menu\LocalActionDefault;
+use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\Core\Routing\UrlGeneratorTrait;
+
+/**
+ * Modifies the 'Place block' local action.
+ */
+class BlockAddLocalAction extends LocalActionDefault {
+  use UrlGeneratorTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getOptions(RouteMatchInterface $route_match) {
+    $options = parent::getOptions($route_match);
+    // If the route specifies a theme, append it to the query string.
+    if ($theme = $route_match->getParameter('theme')) {
+      $options['query']['theme'] = $theme;
+    }
+    return $options;
+  }
+
+}