diff --git a/README.md b/README.md
index 9c876f0..b41d2d5 100644
--- a/README.md
+++ b/README.md
@@ -1738,6 +1738,16 @@ Create index without importing
 Product.reindex(import: false)
 ```
 
+Use a different id
+
+```ruby
+class Product < ApplicationRecord
+  def search_document_id
+    custom_id
+  end
+end
+```
+
 Lazy searching
 
 ```ruby
--
libgit2 0.21.0