diff --git a/client/call.go b/client/call.go
index 167bb05..511600d 100644
--- a/client/call.go
+++ b/client/call.go
@@ -10,7 +10,7 @@ var callStatePool sync.Pool
 var zeroTime time.Time
 
 type CallState struct {
-	ID       interface{}
+	ID       uint64
 	Method   string
 	Args     interface{}
 	Result   interface{}
diff --git a/client/client.go b/client/client.go
index ad8cc50..baebb3a 100644
--- a/client/client.go
+++ b/client/client.go
@@ -34,7 +34,7 @@ type client struct {
 	conn net.Conn
 
 	pendingRequestsCount uint32
-	pendingRequests      map[interface{}]*CallState
+	pendingRequests      map[uint64]*CallState
 	pendingRequestsLock  sync.Mutex
 
 	requestQueueChan chan *CallState
@@ -56,7 +56,7 @@ func (c *client) Connect() error {
 	}
 	c.stopChan = make(chan struct{})
 	c.requestQueueChan = make(chan *CallState, c.ch.GetPendingRequests())
-	c.pendingRequests = make(map[interface{}]*CallState)
+	c.pendingRequests = make(map[uint64]*CallState)
 
 	go c.handleRPC()
 
@@ -297,9 +297,9 @@ func (c *client) rpcReader(readerDone chan<- error) {
 
 func (c *client) responseHandle(codecResponse protocol.ClientCodecResponse) error {
 	c.pendingRequestsLock.Lock()
-	cs, ok := c.pendingRequests[codecResponse.ID()]
+	cs, ok := c.pendingRequests[codecResponse.ID().(uint64)]
 	if ok {
-		delete(c.pendingRequests, codecResponse.ID())
+		delete(c.pendingRequests, codecResponse.ID().(uint64))
 	}
 	c.pendingRequestsLock.Unlock()
 
diff --git a/client/client_handler.go b/client/client_handler.go
index c2b8c58..bd3c946 100644
--- a/client/client_handler.go
+++ b/client/client_handler.go
@@ -16,6 +16,6 @@ type ClientHandler interface {
 	GetRequestTimeout() time.Duration
 	GetPendingRequests() int
 
-	GetRequestID() interface{}
+	GetRequestID() uint64
 	Validate()
 }
diff --git a/client/client_handlers.go b/client/client_handlers.go
index 997cdf8..0ae9620 100644
--- a/client/client_handlers.go
+++ b/client/client_handlers.go
@@ -50,7 +50,7 @@ func (ch *ClientHandlers) GetPendingRequests() int {
 	return ch.PendingRequests
 }
 
-func (ch *ClientHandlers) GetRequestID() interface{} {
+func (ch *ClientHandlers) GetRequestID() uint64 {
 	var id uint64
 	ch.requestIDMtx.Lock()
 	ch.requestID++