diff --git a/ndn-cpp/c/transport/socket-transport.c b/ndn-cpp/c/transport/socket-transport.c
index aef13ac..09a5b57 100644
--- a/ndn-cpp/c/transport/socket-transport.c
+++ b/ndn-cpp/c/transport/socket-transport.c
@@ -67,7 +67,7 @@
   return NDN_ERROR_success;
 }
 
-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)
 {
   if (self->socketDescriptor < 0)
     return NDN_ERROR_SocketTransport_socket_is_not_open;
@@ -115,7 +115,7 @@
 }
 
 ndn_Error ndn_SocketTransport_receive
-  (struct ndn_SocketTransport *self, uint8_t *buffer, unsigned int bufferLength, unsigned int *nBytesOut)
+  (struct ndn_SocketTransport *self, uint8_t *buffer, size_t bufferLength, size_t *nBytesOut)
 {
   if (self->socketDescriptor < 0)
     return NDN_ERROR_SocketTransport_socket_is_not_open;
@@ -124,7 +124,7 @@
   if ((nBytes = recv(self->socketDescriptor, buffer, bufferLength, 0)) == -1)
     return NDN_ERROR_SocketTransport_error_in_recv;
 
-  *nBytesOut = (unsigned int)nBytes;
+  *nBytesOut = (size_t)nBytes;
   
   return NDN_ERROR_success;  
 }
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.
diff --git a/ndn-cpp/c/transport/tcp-transport.h b/ndn-cpp/c/transport/tcp-transport.h
index 05902f9..55f2e8e 100644
--- a/ndn-cpp/c/transport/tcp-transport.h
+++ b/ndn-cpp/c/transport/tcp-transport.h
@@ -45,7 +45,7 @@
  * @param dataLength The number of bytes in data.
  * @return 0 for success, else an error code.
  */
-static inline ndn_Error ndn_TcpTransport_send(struct ndn_TcpTransport *self, uint8_t *data, unsigned int dataLength)
+static inline ndn_Error ndn_TcpTransport_send(struct ndn_TcpTransport *self, uint8_t *data, size_t dataLength)
 {
   return ndn_SocketTransport_send(&self->base, data, dataLength);
 }
@@ -72,7 +72,7 @@
  * @return 0 for success, else an error code.
  */
 static inline ndn_Error ndn_TcpTransport_receive
-  (struct ndn_TcpTransport *self, uint8_t *buffer, unsigned int bufferLength, unsigned int *nBytes)
+  (struct ndn_TcpTransport *self, uint8_t *buffer, size_t bufferLength, size_t *nBytes)
 {
   return ndn_SocketTransport_receive(&self->base, buffer, bufferLength, nBytes);
 }
diff --git a/ndn-cpp/c/transport/udp-transport.h b/ndn-cpp/c/transport/udp-transport.h
index fc9a173..20d106b 100644
--- a/ndn-cpp/c/transport/udp-transport.h
+++ b/ndn-cpp/c/transport/udp-transport.h
@@ -45,7 +45,7 @@
  * @param dataLength The number of bytes in data.
  * @return 0 for success, else an error code.
  */
-static inline ndn_Error ndn_UdpTransport_send(struct ndn_UdpTransport *self, uint8_t *data, unsigned int dataLength)
+static inline ndn_Error ndn_UdpTransport_send(struct ndn_UdpTransport *self, uint8_t *data, size_t dataLength)
 {
   return ndn_SocketTransport_send(&self->base, data, dataLength);
 }
@@ -72,7 +72,7 @@
  * @return 0 for success, else an error code.
  */
 static inline ndn_Error ndn_UdpTransport_receive
-  (struct ndn_UdpTransport *self, uint8_t *buffer, unsigned int bufferLength, unsigned int *nBytes)
+  (struct ndn_UdpTransport *self, uint8_t *buffer, size_t bufferLength, size_t *nBytes)
 {
   return ndn_SocketTransport_receive(&self->base, buffer, bufferLength, nBytes);
 }