diff --git a/etcd/v3/AsyncLeaseKeepAliveAction.hpp b/etcd/v3/AsyncLeaseKeepAliveAction.hpp
index 7458ad0..8d9bfef 100644
--- a/etcd/v3/AsyncLeaseKeepAliveAction.hpp
+++ b/etcd/v3/AsyncLeaseKeepAliveAction.hpp
@@ -16,6 +16,7 @@ using grpc::ClientAsyncResponseReader;
 
 namespace etcdv3 {
 class AsyncLeaseKeepAliveAction : public etcdv3::Action {
+  enum class Type { READ = 1, WRITE = 2, CONNECT = 3, WRITES_DONE = 4, FINISH = 5 };
  public:
   AsyncLeaseKeepAliveAction(etcdv3::ActionParameters param);
   AsyncLeaseKeepAliveResponse ParseResponse();
@@ -24,8 +25,6 @@ class AsyncLeaseKeepAliveAction : public etcdv3::Action {
  private:
   LeaseKeepAliveResponse reply;
   std::unique_ptr<ClientAsyncReaderWriter<LeaseKeepAliveRequest, LeaseKeepAliveResponse>> stream;
-
-  char* doneTag = "writes done";
 };
 }  // namespace etcdv3
 
diff --git a/src/v3/AsyncLeaseKeepAliveAction.cpp b/src/v3/AsyncLeaseKeepAliveAction.cpp
index a23c174..0c787d0 100644
--- a/src/v3/AsyncLeaseKeepAliveAction.cpp
+++ b/src/v3/AsyncLeaseKeepAliveAction.cpp
@@ -8,10 +8,7 @@ using etcdserverpb::RangeRequest;
 using etcdserverpb::RangeResponse;
 
 etcdv3::AsyncLeaseKeepAliveAction::AsyncLeaseKeepAliveAction(etcdv3::ActionParameters param) : etcdv3::Action(param) {
-  char* createTag = "create";
-  char* writeTag = "write";
-
-  stream = parameters.lease_stub->AsyncLeaseKeepAlive(&context, &cq_, (void*)createTag);
+  stream = parameters.lease_stub->AsyncLeaseKeepAlive(&context, &cq_, reinterpret_cast<void*>(Type::CONNECT));
 
   LeaseKeepAliveRequest request;
   request.set_id(parameters.lease_id);
@@ -19,15 +16,15 @@ etcdv3::AsyncLeaseKeepAliveAction::AsyncLeaseKeepAliveAction(etcdv3::ActionParam
   // wait "create" success (the stream becomes ready)
   void* got_tag;
   bool ok = false;
-  if (cq_.Next(&got_tag, &ok) && ok && got_tag == (void*)createTag) {
-    stream->Write(request, (void*)writeTag);
+  if (cq_.Next(&got_tag, &ok) && ok && got_tag == reinterpret_cast<void*>(Type::CONNECT)) {
+    stream->Write(request, reinterpret_cast<void*>(Type::WRITE));
   } else {
     throw std::runtime_error("failed to create a keepalive connection");
   }
 
   // wait "write" (LeaseKeepAliveRequest) success, and start to read the first
   // reply
-  if (cq_.Next(&got_tag, &ok) && ok && got_tag == (void*)writeTag) {
+  if (cq_.Next(&got_tag, &ok) && ok && got_tag == reinterpret_cast<void*>(Type::WRITE)) {
     stream->Read(&reply, (void*)this);
   } else {
     throw std::runtime_error("failed to write LeaseKeepAliveRequest to server");
@@ -42,14 +39,14 @@ void etcdv3::AsyncLeaseKeepAliveAction::waitForResponse() {
     if (ok == false) {
       break;
     }
-    if (got_tag == (void*)doneTag) {
+    if (got_tag == reinterpret_cast<void*>(Type::WRITES_DONE)) {
       cq_.Shutdown();
       break;
     }
     if (got_tag == (void*)this)  // read tag
     {
       if (reply.ByteSize()) {
-        stream->WritesDone((void*)doneTag);
+        stream->WritesDone(reinterpret_cast<void*>(Type::WRITES_DONE));
       } else {
         stream->Read(&reply, (void*)this);
       }