diff --git a/core/modules/block/block.module b/core/modules/block/block.module
index 7e39da4..37ff88f 100644
--- a/core/modules/block/block.module
+++ b/core/modules/block/block.module
@@ -222,7 +222,7 @@ function template_preprocess_block(&$variables) {
 
   // Create a valid HTML ID and make sure it is unique.
   if (!empty($variables['elements']['#id'])) {
-    $variables['attributes']['id'] = Html::getUniqueId('block-' . $variables['elements']['#id']);
+    $variables['attributes']['data-id'] = Html::getUniqueId('block-' . $variables['elements']['#id']);
   }
 
   // Proactively add aria-describedby if possible to improve accessibility.