diff --git a/CHANGELOG.md b/CHANGELOG.md
index d59685c..c9fe784 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,7 @@
 ## [Unreleased]
 
 - Add `skip-empty` option to prevent generating empty scaffolding for proto files without services - [#21](https://github.com/collectiveidea/protoc-gen-twirp_ruby/pull/21) 
-- Refactor code generator to improve internal readability - [#12](https://github.com/collectiveidea/protoc-gen-twirp_ruby/pull/12), [#13](https://github.com/collectiveidea/protoc-gen-twirp_ruby/pull/13)
+- Refactor code generator to improve internal readability - [#12](https://github.com/collectiveidea/protoc-gen-twirp_ruby/pull/12), [#13](https://github.com/collectiveidea/protoc-gen-twirp_ruby/pull/13), [#22](https://github.com/collectiveidea/protoc-gen-twirp_ruby/pull/22)
 - Remove unnecessary extra files from packaged gem - [#11](https://github.com/collectiveidea/protoc-gen-twirp_ruby/pull/11)
 
 ## [1.0.0] - 2024-05-10
diff --git a/lib/twirp/protoc_plugin/code_generator.rb b/lib/twirp/protoc_plugin/code_generator.rb
index 9ad1854..9725aee 100644
--- a/lib/twirp/protoc_plugin/code_generator.rb
+++ b/lib/twirp/protoc_plugin/code_generator.rb
@@ -3,6 +3,7 @@
 require_relative "../../google/protobuf/compiler/plugin_pb"
 require_relative "../../core_ext/string/camel_case"
 require_relative "../../core_ext/string/snake_case"
+require_relative "descriptor_ext/service_descriptor_proto_ext"
 require "stringio"
 
 module Twirp
@@ -52,14 +53,7 @@ def generate
           output << "\n" if index > 0
 
           service_name = service.name
-          # The generated service class name should end in "Service"; Only append the
-          # suffix if the service is not already well-named.
-          service_class_name = if service_name.end_with?("Service")
-            service_name
-          else
-            service_name + "Service"
-          end
-          service_class_name = service_class_name.camel_case
+          service_class_name = service.service_class_name
 
           # Generate service class
           output << line("class #{service_class_name} < ::Twirp::Service", indent_level)
@@ -76,8 +70,7 @@ def generate
 
           # Generate client class
 
-          # Strip the "Service" suffix if present for better readability.
-          client_class_name = (service_name.delete_suffix("Service") + "Client").camel_case
+          client_class_name = service.client_class_name
 
           output << "\n"
           output << line("class #{client_class_name} < ::Twirp::Client", indent_level)
diff --git a/lib/twirp/protoc_plugin/descriptor_ext/service_descriptor_proto_ext.rb b/lib/twirp/protoc_plugin/descriptor_ext/service_descriptor_proto_ext.rb
new file mode 100644
index 0000000..a5d41f9
--- /dev/null
+++ b/lib/twirp/protoc_plugin/descriptor_ext/service_descriptor_proto_ext.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require_relative "../../../core_ext/string/camel_case"
+
+class Google::Protobuf::ServiceDescriptorProto
+  def service_class_name
+    # The generated service class name should end in "Service"; A well-named
+    # service may already end with "Service" but we can't guarantee it. Use
+    # class_name_without_service_suffix to #avoid "ServiceService"
+    class_name_without_service_suffix + "Service"
+  end
+
+  def client_class_name
+    class_name_without_service_suffix + "Client"
+  end
+
+  private
+
+  def class_name_without_service_suffix
+    name.delete_suffix("Service").camel_case
+  end
+end
diff --git a/spec/twirp/protoc_plugin/descriptor_ext/service_descriptor_proto_ext_spec.rb b/spec/twirp/protoc_plugin/descriptor_ext/service_descriptor_proto_ext_spec.rb
new file mode 100644
index 0000000..75515ed
--- /dev/null
+++ b/spec/twirp/protoc_plugin/descriptor_ext/service_descriptor_proto_ext_spec.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+RSpec.describe Google::Protobuf::ServiceDescriptorProto do
+  describe "#service_class_name" do
+    it "appends \"Service\" when the service is not well-named" do
+      service = Google::Protobuf::ServiceDescriptorProto.new(name: "HelloWorld")
+      expect(service.service_class_name).to eq("HelloWorldService")
+    end
+
+    it "does not alter the service name when the service is well-named" do
+      service = Google::Protobuf::ServiceDescriptorProto.new(name: "HelloWorldService")
+      expect(service.service_class_name).to eq("HelloWorldService")
+    end
+  end
+
+  describe "#client_class_name" do
+    it "appends \"Client\" when the service is not well-named" do
+      service = Google::Protobuf::ServiceDescriptorProto.new(name: "HelloWorld")
+      expect(service.client_class_name).to eq("HelloWorldClient")
+    end
+
+    it "trims \"Service\" and appends \"Client\" when the service is well-named" do
+      service = Google::Protobuf::ServiceDescriptorProto.new(name: "HelloWorldService")
+      expect(service.client_class_name).to eq("HelloWorldClient")
+    end
+  end
+end