diff --git a/CHANGELOG.md b/CHANGELOG.md
index a12ad50..6e37f97 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,7 +12,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+* [#16](https://github.com/jcagarcia/grape-idempotency/pull/16): Changing error response code to 422 for conflict - [@Flip120](https://github.com/Flip120).
 * [#11](https://github.com/jcagarcia/grape-idempotency/pull/11): Changing error response formats - [@Flip120](https://github.com/Flip120).
+
 * Your contribution here.
 
 ### Feature
diff --git a/README.md b/README.md
index 40fd264..86b39b3 100644
--- a/README.md
+++ b/README.md
@@ -74,7 +74,7 @@ To execute an idempotent request, simply request your user to include an extra `
 
 This gem operates by storing the initial request's status code and response body, regardless of whether the request succeeded or failed, using a specific idempotency key. Subsequent requests with the same key will consistently yield the same result, even if there were 500 errors.
 
-Keys are automatically removed from the system if they are at least 24 hours old, and a new request is generated when a key is reused after the original has been removed. The idempotency layer compares incoming parameters to those of the original request and returns a `409 - Conflict` status code if they don't match, preventing accidental misuse.
+Keys are automatically removed from the system if they are at least 24 hours old, and a new request is generated when a key is reused after the original has been removed. The idempotency layer compares incoming parameters to those of the original request and returns a `422 - Unprocessable Entity` status code if they don't match, preventing accidental misuse.
 If a request is received while another one with the same idempotency key is still being processed the idempotency layer returns a `409 - Conflict` status
 
 Results are only saved if an API endpoint begins its execution. If incoming parameters fail validation or if the request conflicts with another one executing concurrently, no idempotent result is stored because no API endpoint has initiated execution. In such cases, retrying these requests is safe.
diff --git a/lib/grape/idempotency.rb b/lib/grape/idempotency.rb
index 8bfa3d6..0db35a0 100644
--- a/lib/grape/idempotency.rb
+++ b/lib/grape/idempotency.rb
@@ -31,7 +31,7 @@ def idempotent(grape, required: false, &block)
 
         cached_request = get_from_cache(idempotency_key)
         if cached_request && (cached_request["params"] != grape.request.params || cached_request["path"] != grape.request.path)
-          grape.error!(configuration.conflict_error_response, 409)
+          grape.error!(configuration.conflict_error_response, 422)
         elsif cached_request && cached_request["processing"] == true
           grape.error!(configuration.processing_response, 409)
         elsif cached_request
@@ -44,8 +44,7 @@ def idempotent(grape, required: false, &block)
         original_request_id = get_request_id(grape.request.headers)
         success = store_processing_request(idempotency_key, grape.request.path, grape.request.params, original_request_id)
         if !success
-          grape.status 409
-          return configuration.processing_response
+          grape.error!(configuration.processing_response, 409)
         end
 
         response = catch(:error) do
diff --git a/spec/idempotent_spec.rb b/spec/idempotent_spec.rb
index 2d1a7b9..cb34ffd 100644
--- a/spec/idempotent_spec.rb
+++ b/spec/idempotent_spec.rb
@@ -161,7 +161,7 @@
 
                 header "idempotency-key", idempotency_key
                 post 'payments?locale=en', { amount: 800_00 }.to_json
-                expect(last_response.status).to eq(409)
+                expect(last_response.status).to eq(422)
                 expect(last_response.body).to eq("{\"title\":\"Idempotency-Key is already used\",\"detail\":\"This operation is idempotent and it requires correct usage of Idempotency Key. Idempotency Key MUST not be reused across different payloads of this operation.\"}")
               end
             end
@@ -191,7 +191,7 @@
 
                 header "idempotency-key", idempotency_key
                 post 'refunds?locale=es', { amount: 100_00 }.to_json
-                expect(last_response.status).to eq(409)
+                expect(last_response.status).to eq(422)
                 expect(last_response.body).to eq("{\"title\":\"Idempotency-Key is already used\",\"detail\":\"This operation is idempotent and it requires correct usage of Idempotency Key. Idempotency Key MUST not be reused across different payloads of this operation.\"}")
               end
             end
@@ -245,7 +245,7 @@
                 post 'payments?locale=es', { amount: 100_00 }.to_json
 
                 expect(last_response.status).to eq(409)
-                expect(last_response.body).to eq("{\"title\"=>\"A request is outstanding for this Idempotency-Key\", \"detail\"=>\"A request with the same idempotent key for the same operation is being processed or is outstanding.\"}")
+                expect(last_response.body).to eq("{\"title\":\"A request is outstanding for this Idempotency-Key\",\"detail\":\"A request with the same idempotent key for the same operation is being processed or is outstanding.\"}")
               end
             end
 
@@ -530,7 +530,7 @@
 
         header "idempotency-key", idempotency_key
         post 'payments?locale=en', { amount: 800_00 }.to_json
-        expect(last_response.status).to eq(409)
+        expect(last_response.status).to eq(422)
         expect(last_response.body).to eq("{\"error\":\"An error wadus with conflict\",\"status\":409,\"message\":\"You are using the same idempotency key for two different requests\"}")
       end
     end