diff --git a/BasiliskII/src/slirp/misc.c b/BasiliskII/src/slirp/misc.c
index 8af63a18..233c965f 100644
--- a/BasiliskII/src/slirp/misc.c
+++ b/BasiliskII/src/slirp/misc.c
@@ -822,7 +822,7 @@ fd_nonblock(fd)
 	int fd;
 {
 #if defined USE_FIONBIO && defined FIONBIO
-	int opt = 1;
+	ioctlsockopt_t opt = 1;
 	
 	ioctlsocket(fd, FIONBIO, &opt);
 #else
@@ -839,7 +839,7 @@ fd_block(fd)
 	int fd;
 {
 #if defined USE_FIONBIO && defined FIONBIO
-	int opt = 0;
+	ioctlsockopt_t opt = 0;
 	
 	ioctlsocket(fd, FIONBIO, &opt);
 #else
diff --git a/BasiliskII/src/slirp/slirp.h b/BasiliskII/src/slirp/slirp.h
index 698a2b3f..5a48c87f 100644
--- a/BasiliskII/src/slirp/slirp.h
+++ b/BasiliskII/src/slirp/slirp.h
@@ -19,19 +19,29 @@ typedef uint16_t u_int16_t;
 typedef uint32_t u_int32_t;
 typedef uint64_t u_int64_t;
 typedef char *caddr_t;
+typedef int socklen_t;
+typedef unsigned long ioctlsockopt_t;
 
 # include <windows.h>
 # include <winsock2.h>
 # include <sys/timeb.h>
 # include <iphlpapi.h>
 
+# define USE_FIONBIO 1
 # define EWOULDBLOCK WSAEWOULDBLOCK
 # define EINPROGRESS WSAEINPROGRESS
 # define ENOTCONN WSAENOTCONN
 # define EHOSTUNREACH WSAEHOSTUNREACH
 # define ENETUNREACH WSAENETUNREACH
 # define ECONNREFUSED WSAECONNREFUSED
+
+/* Basilisk II Router defines those */
+# define udp_read_completion slirp_udp_read_completion
+# define write_udp slirp_write_udp
+# define init_udp slirp_init_udp
+# define final_udp slirp_final_udp
 #else
+typedef int ioctlsockopt_t;
 # define ioctlsocket ioctl
 # define closesocket(s) close(s)
 # define O_BINARY 0
diff --git a/BasiliskII/src/slirp/socket.c b/BasiliskII/src/slirp/socket.c
index ce874e0f..f2afd068 100644
--- a/BasiliskII/src/slirp/socket.c
+++ b/BasiliskII/src/slirp/socket.c
@@ -415,7 +415,8 @@ sorecvfrom(so)
 	  udp_detach(so);
 	} else {                            	/* A "normal" UDP packet */
 	  struct mbuf *m;
-	  int len, n;
+	  int len;
+	  ioctlsockopt_t n;
 
 	  if (!(m = m_get())) return;
 	  m->m_data += if_maxlinkhdr;