diff --git a/lib/committer/commit_generator.rb b/lib/committer/commit_generator.rb
index 5de0d4f..27c08cf 100644
--- a/lib/committer/commit_generator.rb
+++ b/lib/committer/commit_generator.rb
@@ -70,8 +70,8 @@ def parse_response(response)
       end
     end
 
-    def prepare_commit_message
-      client = Clients::ClaudeClient.new
+    def prepare_commit_message(client_class = Clients::ClaudeClient)
+      client = client_class.new
 
       prompt = build_commit_prompt
       response = client.post(prompt)
diff --git a/spec/committer/commit_generator_spec.rb b/spec/committer/commit_generator_spec.rb
index 9d12c19..2639849 100644
--- a/spec/committer/commit_generator_spec.rb
+++ b/spec/committer/commit_generator_spec.rb
@@ -200,5 +200,23 @@
         expect(result[:body]).to include('Incremented patch version')
       end
     end
+
+    context 'when called with a different client' do
+      let(:client_class) { class_double('Clients::SomeOtherClient', new: client_instance).as_stubbed_const }
+      let(:client_instance) { instance_double('Clients::SomeOtherClient', post: nil) }
+      let(:generator) { described_class.new(diff, commit_context) }
+
+      before do
+        allow(generator).to receive(:build_commit_prompt).and_return('my prompt')
+        allow(generator).to receive(:parse_response)
+        allow(client_instance).to receive(:post)
+      end
+
+      it 'builds the prompt and passes it to the client' do
+        generator.prepare_commit_message(client_class)
+
+        expect(client_instance).to have_received(:post).with('my prompt')
+      end
+    end
   end
 end