diff --git a/CHANGELOG.md b/CHANGELOG.md
index 328bca3..98cf336 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Support for Ruby 3.2
 - Support for Rails 7.1
 
+### Changed
+
+- Extracted `KeycloakOauth::DuplicationError` into a separate file to please the Zeitwerk loader.
+
 ## [2.0.1] - 2022-06-16
 
 ### Changed
diff --git a/app/services/keycloak_oauth/duplication_error.rb b/app/services/keycloak_oauth/duplication_error.rb
new file mode 100644
index 0000000..5848b58
--- /dev/null
+++ b/app/services/keycloak_oauth/duplication_error.rb
@@ -0,0 +1,3 @@
+module KeycloakOauth
+  class DuplicationError < StandardError; end
+end
diff --git a/app/services/keycloak_oauth/post_users_service.rb b/app/services/keycloak_oauth/post_users_service.rb
index 970711f..b099254 100644
--- a/app/services/keycloak_oauth/post_users_service.rb
+++ b/app/services/keycloak_oauth/post_users_service.rb
@@ -1,8 +1,8 @@
 require 'net/http'
+require 'keycloak_oauth/authorizable_error'
+require 'keycloak_oauth/duplication_error'
 
 module KeycloakOauth
-  class DuplicationError < StandardError; end
-
   class PostUsersService < KeycloakOauth::AuthorizableService
     attr_reader :request_params, :connection, :user_params