diff --git a/libraries/Ethernet/utility/socket.cpp b/libraries/Ethernet/utility/socket.cpp
index 03ff8504c..fd3e4426a 100644
--- a/libraries/Ethernet/utility/socket.cpp
+++ b/libraries/Ethernet/utility/socket.cpp
@@ -143,10 +143,10 @@ uint16_t send(SOCKET s, const uint8_t * buf, uint16_t len)
  * 		
  * @return	received data size for success else -1.
  */
-uint16_t recv(SOCKET s, uint8_t *buf, uint16_t len)
+int16_t recv(SOCKET s, uint8_t *buf, int16_t len)
 {
   // Check how much data is available
-  uint16_t ret = W5100.getRXReceivedSize(s);
+  int16_t ret = W5100.getRXReceivedSize(s);
   if ( ret == 0 )
   {
     // No data available.
diff --git a/libraries/Ethernet/utility/socket.h b/libraries/Ethernet/utility/socket.h
index 37ea93f3d..45e0fb3e8 100755
--- a/libraries/Ethernet/utility/socket.h
+++ b/libraries/Ethernet/utility/socket.h
@@ -9,7 +9,7 @@ extern uint8_t connect(SOCKET s, uint8_t * addr, uint16_t port); // Establish TC
 extern void disconnect(SOCKET s); // disconnect the connection
 extern uint8_t listen(SOCKET s);	// Establish TCP connection (Passive connection)
 extern uint16_t send(SOCKET s, const uint8_t * buf, uint16_t len); // Send data (TCP)
-extern uint16_t recv(SOCKET s, uint8_t * buf, uint16_t len);	// Receive data (TCP)
+extern int16_t recv(SOCKET s, uint8_t * buf, int16_t len);	// Receive data (TCP)
 extern uint16_t peek(SOCKET s, uint8_t *buf);
 extern uint16_t sendto(SOCKET s, const uint8_t * buf, uint16_t len, uint8_t * addr, uint16_t port); // Send data (UDP/IP RAW)
 extern uint16_t recvfrom(SOCKET s, uint8_t * buf, uint16_t len, uint8_t * addr, uint16_t *port); // Receive data (UDP/IP RAW)