diff --git a/ndn-cpp/c/transport/socket-transport.h b/ndn-cpp/c/transport/socket-transport.h
index e1388c3..b0a0979 100644
--- a/ndn-cpp/c/transport/socket-transport.h
+++ b/ndn-cpp/c/transport/socket-transport.h
@@ -50,7 +50,7 @@
  * @param dataLength The number of bytes in data.
  * @return 0 for success, else an error code.
  */
-ndn_Error ndn_SocketTransport_send(struct ndn_SocketTransport *self, uint8_t *data, unsigned int dataLength);
+ndn_Error ndn_SocketTransport_send(struct ndn_SocketTransport *self, uint8_t *data, size_t dataLength);
 
 /**
  * Check if there is data ready on the socket to be received with ndn_SocketTransport_receive.
@@ -71,7 +71,7 @@
  * @return 0 for success, else an error code.
  */
 ndn_Error ndn_SocketTransport_receive
-  (struct ndn_SocketTransport *self, uint8_t *buffer, unsigned int bufferLength, unsigned int *nBytes);
+  (struct ndn_SocketTransport *self, uint8_t *buffer, size_t bufferLength, size_t *nBytes);
 
 /**
  * Close the socket.