diff --git a/ndn-cpp/transport/TcpTransport.hpp b/ndn-cpp/transport/TcpTransport.hpp
index 8b714e8..fc57e54 100644
--- a/ndn-cpp/transport/TcpTransport.hpp
+++ b/ndn-cpp/transport/TcpTransport.hpp
@@ -26,7 +26,7 @@
    */
   virtual void connect(NDN &ndn);
   
-  virtual void send(unsigned char *data, unsigned int dataLength);
+  virtual void send(const unsigned char *data, unsigned int dataLength);
 
   virtual void tempReceive();