diff --git a/test/cpp/end2end/test_service_impl.cc b/test/cpp/end2end/test_service_impl.cc
index bd12d76fd51..3ef49e6612a 100644
--- a/test/cpp/end2end/test_service_impl.cc
+++ b/test/cpp/end2end/test_service_impl.cc
@@ -501,19 +501,19 @@ CallbackTestServiceImpl::ResponseStream(
                             std::to_string(num_msgs_sent_));
       if (num_msgs_sent_ == server_responses_to_send_ - 1 &&
           server_coalescing_api_ != 0) {
-        num_msgs_sent_++;
         {
           std::lock_guard<std::mutex> l(finish_mu_);
           if (!finished_) {
+            num_msgs_sent_++;
             StartWriteLast(&response_, WriteOptions());
           }
         }
         // If we use WriteLast, we shouldn't wait before attempting Finish
         FinishOnce(Status::OK);
       } else {
-        num_msgs_sent_++;
         std::lock_guard<std::mutex> l(finish_mu_);
         if (!finished_) {
+          num_msgs_sent_++;
           StartWrite(&response_);
         }
       }