diff --git a/server/modbus.go b/server/modbus.go
index b6ce6b2..2b5a75b 100644
--- a/server/modbus.go
+++ b/server/modbus.go
@@ -9,7 +9,7 @@ import (
 
 // ModbusTCPAssembler assembles read data into complete packets and calls ModbusHandler with assembled packet
 type ModbusTCPAssembler struct {
-	handler  ModbusHandler
+	Handler  ModbusHandler
 	received bytes.Buffer
 }
 
@@ -29,7 +29,7 @@ func (m *ModbusTCPAssembler) ReceiveRead(ctx context.Context, received []byte, b
 		return err.(*packet.ErrorParseTCP).Bytes(), false
 	}
 
-	resp, err := m.handler.Handle(ctx, p)
+	resp, err := m.Handler.Handle(ctx, p)
 	if err != nil {
 		var target *packet.ErrorParseTCP
 		if errors.As(err, &target) {
diff --git a/server/server.go b/server/server.go
index 82dbab9..ef58ec8 100644
--- a/server/server.go
+++ b/server/server.go
@@ -112,7 +112,7 @@ type ContextRemoteAddr struct{}
 func (s *Server) serve(ctx context.Context, listener net.Listener, handler ModbusHandler) error {
 	if s.AssemblerCreatorFunc == nil {
 		s.AssemblerCreatorFunc = func(handler ModbusHandler) PacketAssembler {
-			return &ModbusTCPAssembler{handler: handler}
+			return &ModbusTCPAssembler{Handler: handler}
 		}
 	}
 	onErrorFunc := s.OnErrorFunc