diff --git a/lib/select.c b/lib/select.c
index 0b5af26145..ee04373427 100644
--- a/lib/select.c
+++ b/lib/select.c
@@ -36,7 +36,7 @@
 #ifdef WIN32
 #define VALID_SOCK(s) (1)  /* Win-sockets are not in range [0..FD_SETSIZE> */
 #else
-#define VALID_SOCK(s) ((s) >= 0) && ((s) < FD_SETSIZE))
+#define VALID_SOCK(s) (((s) >= 0) && ((s) < FD_SETSIZE))
 #endif
 
 /*
@@ -49,7 +49,7 @@
  *    0 = timeout
  *    CSELECT_IN | CSELECT_OUT | CSELECT_ERR
  */
-int Curl_select(int readfd, int writefd, int timeout_ms)
+int Curl_select(curl_socket_t readfd, curl_socket_t writefd, int timeout_ms)
 {
 #ifdef HAVE_POLL_FINE
   struct pollfd pfd[2];
diff --git a/lib/select.h b/lib/select.h
index 373ba2164d..b3d9ce3ae1 100644
--- a/lib/select.h
+++ b/lib/select.h
@@ -23,7 +23,6 @@
  * $Id$
  ***************************************************************************/
 
-
 #ifdef HAVE_SYS_POLL_H
 #include <sys/poll.h>
 #else
@@ -44,12 +43,11 @@ struct pollfd
 
 #endif
 
-
 #define CSELECT_IN   0x01
 #define CSELECT_OUT  0x02
 #define CSELECT_ERR  0x04
 
-int Curl_select(int readfd, int writefd, int timeout_ms);
+int Curl_select(curl_socket_t readfd, curl_socket_t writefd, int timeout_ms);
 
 int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms);