diff --git a/README.md b/README.md
index 835c183..fb55242 100644
--- a/README.md
+++ b/README.md
@@ -347,19 +347,6 @@ rating:
 Now the rates will be written on `reviews` table over `rating_rates` and calculation will be on `review_ratings` over `rating_ratings`.
 You can change one table o both of them.
 
-
-## Validation
-
-It is recommended that you add a validation to ensure that the author do not vote multiple times on the same resource and its scope.
-This validation is not inside the gem since you could want make your own custom validation.
-
-```ruby
-validates :author_id, uniqueness: {
-  case_sensitive: false,
-  scope:          %i[author_type resource_id resource_type scopeable_id scopeable_type]
-}
-```
-
 ## Love it!
 
 Via [PayPal](https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=X8HEP2878NDEG&item_name=rating) or [Patreon](https://www.patreon.com/wbotelhos). Thanks! (:
diff --git a/lib/rating/models/rating/rate.rb b/lib/rating/models/rating/rate.rb
index 1d073fb..d7bbf75 100644
--- a/lib/rating/models/rating/rate.rb
+++ b/lib/rating/models/rating/rate.rb
@@ -14,6 +14,11 @@ module Rating
     validates :author, :resource, :value, presence: true
     validates :value, numericality: { greater_than_or_equal_to: 1, less_than_or_equal_to: 100 }
 
+    validates :author_id, uniqueness: {
+      case_sensitive: false,
+      scope:          %i[author_type resource_id resource_type scopeable_id scopeable_type]
+    }
+
     def self.create(author:, metadata:, resource:, scopeable: nil, value:)
       record = find_or_initialize_by(author: author, resource: resource, scopeable: scopeable)
 
diff --git a/spec/models/rate_spec.rb b/spec/models/rate_spec.rb
index eb7518b..7553c95 100644
--- a/spec/models/rate_spec.rb
+++ b/spec/models/rate_spec.rb
@@ -18,4 +18,10 @@ RSpec.describe Rating::Rate do
   it do
     is_expected.to validate_numericality_of(:value).is_less_than_or_equal_to(100).is_less_than_or_equal_to 100
   end
+
+  it do
+    expect(object).to validate_uniqueness_of(:author_id)
+      .scoped_to(%i[author_type resource_id resource_type scopeable_id scopeable_type])
+      .case_insensitive
+  end
 end