diff --git a/extmod/modnetwork.h b/extmod/modnetwork.h
index 39e4d06d69..bbf80bc474 100644
--- a/extmod/modnetwork.h
+++ b/extmod/modnetwork.h
@@ -72,15 +72,11 @@ typedef struct _mod_network_socket_obj_t {
     mp_obj_base_t base;
     mp_obj_t nic;
     mod_network_nic_type_t *nic_type;
-    union {
-        struct {
-            uint8_t domain;
-            uint8_t type;
-            int8_t fileno;
-            uint8_t bound;
-        } u_param;
-        mp_uint_t u_state;
-    };
+    uint32_t domain : 5;
+    uint32_t type   : 5;
+    uint32_t proto  : 5;
+    uint32_t bound  : 1;
+    int32_t fileno  : 16;
     #if MICROPY_PY_USOCKET_EXTENDED_STATE
     // Extended socket state for NICs/ports that need it.
     int32_t timeout;
diff --git a/extmod/modusocket.c b/extmod/modusocket.c
index fea81077c5..e08f8134fd 100644
--- a/extmod/modusocket.c
+++ b/extmod/modusocket.c
@@ -51,16 +51,17 @@ STATIC mp_obj_t socket_make_new(const mp_obj_type_t *type, size_t n_args, size_t
     s->base.type = &socket_type;
     s->nic = MP_OBJ_NULL;
     s->nic_type = NULL;
-    s->u_param.domain = MOD_NETWORK_AF_INET;
-    s->u_param.type = MOD_NETWORK_SOCK_STREAM;
-    s->u_param.fileno = -1;
-    s->u_param.bound = false;
+    s->domain = MOD_NETWORK_AF_INET;
+    s->type = MOD_NETWORK_SOCK_STREAM;
+    s->proto = 0;
+    s->bound = false;
+    s->fileno = -1;
     if (n_args >= 1) {
-        s->u_param.domain = mp_obj_get_int(args[0]);
+        s->domain = mp_obj_get_int(args[0]);
         if (n_args >= 2) {
-            s->u_param.type = mp_obj_get_int(args[1]);
+            s->type = mp_obj_get_int(args[1]);
             if (n_args >= 4) {
-                s->u_param.fileno = mp_obj_get_int(args[3]);
+                s->fileno = mp_obj_get_int(args[3]);
             }
         }
     }
diff --git a/ports/stm32/modnwcc3k.c b/ports/stm32/modnwcc3k.c
index 5dae9d6407..952e535c2d 100644
--- a/ports/stm32/modnwcc3k.c
+++ b/ports/stm32/modnwcc3k.c
@@ -136,13 +136,13 @@ STATIC int cc3k_gethostbyname(mp_obj_t nic, const char *name, mp_uint_t len, uin
 }
 
 STATIC int cc3k_socket_socket(mod_network_socket_obj_t *socket, int *_errno) {
-    if (socket->u_param.domain != MOD_NETWORK_AF_INET) {
+    if (socket->domain != MOD_NETWORK_AF_INET) {
         *_errno = MP_EAFNOSUPPORT;
         return -1;
     }
 
     mp_uint_t type;
-    switch (socket->u_param.type) {
+    switch (socket->type) {
         case MOD_NETWORK_SOCK_STREAM:
             type = SOCK_STREAM;
             break;
@@ -168,23 +168,23 @@ STATIC int cc3k_socket_socket(mod_network_socket_obj_t *socket, int *_errno) {
     cc3k_reset_fd_closed_state(fd);
 
     // store state of this socket
-    socket->u_state = fd;
+    socket->fileno = fd;
 
     // make accept blocking by default
     int optval = SOCK_OFF;
     socklen_t optlen = sizeof(optval);
-    CC3000_EXPORT(setsockopt)(socket->u_state, SOL_SOCKET, SOCKOPT_ACCEPT_NONBLOCK, &optval, optlen);
+    CC3000_EXPORT(setsockopt)(socket->fileno, SOL_SOCKET, SOCKOPT_ACCEPT_NONBLOCK, &optval, optlen);
 
     return 0;
 }
 
 STATIC void cc3k_socket_close(mod_network_socket_obj_t *socket) {
-    CC3000_EXPORT(closesocket)(socket->u_state);
+    CC3000_EXPORT(closesocket)(socket->fileno);
 }
 
 STATIC int cc3k_socket_bind(mod_network_socket_obj_t *socket, byte *ip, mp_uint_t port, int *_errno) {
     MAKE_SOCKADDR(addr, ip, port)
-    int ret = CC3000_EXPORT(bind)(socket->u_state, &addr, sizeof(addr));
+    int ret = CC3000_EXPORT(bind)(socket->fileno, &addr, sizeof(addr));
     if (ret != 0) {
         *_errno = ret;
         return -1;
@@ -193,7 +193,7 @@ STATIC int cc3k_socket_bind(mod_network_socket_obj_t *socket, byte *ip, mp_uint_
 }
 
 STATIC int cc3k_socket_listen(mod_network_socket_obj_t *socket, mp_int_t backlog, int *_errno) {
-    int ret = CC3000_EXPORT(listen)(socket->u_state, backlog);
+    int ret = CC3000_EXPORT(listen)(socket->fileno, backlog);
     if (ret != 0) {
         *_errno = ret;
         return -1;
@@ -206,7 +206,7 @@ STATIC int cc3k_socket_accept(mod_network_socket_obj_t *socket, mod_network_sock
     int fd;
     sockaddr addr;
     socklen_t addr_len = sizeof(addr);
-    if ((fd = CC3000_EXPORT(accept)(socket->u_state, &addr, &addr_len)) < 0) {
+    if ((fd = CC3000_EXPORT(accept)(socket->fileno, &addr, &addr_len)) < 0) {
         if (fd == SOC_IN_PROGRESS) {
             *_errno = MP_EAGAIN;
         } else {
@@ -219,7 +219,7 @@ STATIC int cc3k_socket_accept(mod_network_socket_obj_t *socket, mod_network_sock
     cc3k_reset_fd_closed_state(fd);
 
     // store state in new socket object
-    socket2->u_state = fd;
+    socket2->fileno = fd;
 
     // return ip and port
     // it seems CC3000 returns little endian for accept??
@@ -235,7 +235,7 @@ STATIC int cc3k_socket_accept(mod_network_socket_obj_t *socket, mod_network_sock
 
 STATIC int cc3k_socket_connect(mod_network_socket_obj_t *socket, byte *ip, mp_uint_t port, int *_errno) {
     MAKE_SOCKADDR(addr, ip, port)
-    int ret = CC3000_EXPORT(connect)(socket->u_state, &addr, sizeof(addr));
+    int ret = CC3000_EXPORT(connect)(socket->fileno, &addr, sizeof(addr));
     if (ret != 0) {
         *_errno = CC3000_EXPORT(errno);
         return -1;
@@ -244,8 +244,8 @@ STATIC int cc3k_socket_connect(mod_network_socket_obj_t *socket, byte *ip, mp_ui
 }
 
 STATIC mp_uint_t cc3k_socket_send(mod_network_socket_obj_t *socket, const byte *buf, mp_uint_t len, int *_errno) {
-    if (cc3k_get_fd_closed_state(socket->u_state)) {
-        CC3000_EXPORT(closesocket)(socket->u_state);
+    if (cc3k_get_fd_closed_state(socket->fileno)) {
+        CC3000_EXPORT(closesocket)(socket->fileno);
         *_errno = MP_EPIPE;
         return -1;
     }
@@ -255,7 +255,7 @@ STATIC mp_uint_t cc3k_socket_send(mod_network_socket_obj_t *socket, const byte *
     mp_int_t bytes = 0;
     while (bytes < len) {
         int n = MIN((len - bytes), MAX_TX_PACKET);
-        n = CC3000_EXPORT(send)(socket->u_state, (uint8_t *)buf + bytes, n, 0);
+        n = CC3000_EXPORT(send)(socket->fileno, (uint8_t *)buf + bytes, n, 0);
         if (n <= 0) {
             *_errno = CC3000_EXPORT(errno);
             return -1;
@@ -268,18 +268,18 @@ STATIC mp_uint_t cc3k_socket_send(mod_network_socket_obj_t *socket, const byte *
 
 STATIC mp_uint_t cc3k_socket_recv(mod_network_socket_obj_t *socket, byte *buf, mp_uint_t len, int *_errno) {
     // check the socket is open
-    if (cc3k_get_fd_closed_state(socket->u_state)) {
+    if (cc3k_get_fd_closed_state(socket->fileno)) {
         // socket is closed, but CC3000 may have some data remaining in buffer, so check
         fd_set rfds;
         FD_ZERO(&rfds);
-        FD_SET(socket->u_state, &rfds);
+        FD_SET(socket->fileno, &rfds);
         cc3000_timeval tv;
         tv.tv_sec = 0;
         tv.tv_usec = 1;
-        int nfds = CC3000_EXPORT(select)(socket->u_state + 1, &rfds, NULL, NULL, &tv);
-        if (nfds == -1 || !FD_ISSET(socket->u_state, &rfds)) {
+        int nfds = CC3000_EXPORT(select)(socket->fileno + 1, &rfds, NULL, NULL, &tv);
+        if (nfds == -1 || !FD_ISSET(socket->fileno, &rfds)) {
             // no data waiting, so close socket and return 0 data
-            CC3000_EXPORT(closesocket)(socket->u_state);
+            CC3000_EXPORT(closesocket)(socket->fileno);
             return 0;
         }
     }
@@ -288,7 +288,7 @@ STATIC mp_uint_t cc3k_socket_recv(mod_network_socket_obj_t *socket, byte *buf, m
     len = MIN(len, MAX_RX_PACKET);
 
     // do the recv
-    int ret = CC3000_EXPORT(recv)(socket->u_state, buf, len, 0);
+    int ret = CC3000_EXPORT(recv)(socket->fileno, buf, len, 0);
     if (ret < 0) {
         *_errno = CC3000_EXPORT(errno);
         return -1;
@@ -299,7 +299,7 @@ STATIC mp_uint_t cc3k_socket_recv(mod_network_socket_obj_t *socket, byte *buf, m
 
 STATIC mp_uint_t cc3k_socket_sendto(mod_network_socket_obj_t *socket, const byte *buf, mp_uint_t len, byte *ip, mp_uint_t port, int *_errno) {
     MAKE_SOCKADDR(addr, ip, port)
-    int ret = CC3000_EXPORT(sendto)(socket->u_state, (byte *)buf, len, 0, (sockaddr *)&addr, sizeof(addr));
+    int ret = CC3000_EXPORT(sendto)(socket->fileno, (byte *)buf, len, 0, (sockaddr *)&addr, sizeof(addr));
     if (ret < 0) {
         *_errno = CC3000_EXPORT(errno);
         return -1;
@@ -310,7 +310,7 @@ STATIC mp_uint_t cc3k_socket_sendto(mod_network_socket_obj_t *socket, const byte
 STATIC mp_uint_t cc3k_socket_recvfrom(mod_network_socket_obj_t *socket, byte *buf, mp_uint_t len, byte *ip, mp_uint_t *port, int *_errno) {
     sockaddr addr;
     socklen_t addr_len = sizeof(addr);
-    mp_int_t ret = CC3000_EXPORT(recvfrom)(socket->u_state, buf, len, 0, &addr, &addr_len);
+    mp_int_t ret = CC3000_EXPORT(recvfrom)(socket->fileno, buf, len, 0, &addr, &addr_len);
     if (ret < 0) {
         *_errno = CC3000_EXPORT(errno);
         return -1;
@@ -320,7 +320,7 @@ STATIC mp_uint_t cc3k_socket_recvfrom(mod_network_socket_obj_t *socket, byte *bu
 }
 
 STATIC int cc3k_socket_setsockopt(mod_network_socket_obj_t *socket, mp_uint_t level, mp_uint_t opt, const void *optval, mp_uint_t optlen, int *_errno) {
-    int ret = CC3000_EXPORT(setsockopt)(socket->u_state, level, opt, optval, optlen);
+    int ret = CC3000_EXPORT(setsockopt)(socket->fileno, level, opt, optval, optlen);
     if (ret < 0) {
         *_errno = CC3000_EXPORT(errno);
         return -1;
@@ -340,14 +340,14 @@ STATIC int cc3k_socket_settimeout(mod_network_socket_obj_t *socket, mp_uint_t ti
             // set blocking mode
             optval = SOCK_OFF;
         }
-        ret = CC3000_EXPORT(setsockopt)(socket->u_state, SOL_SOCKET, SOCKOPT_RECV_NONBLOCK, &optval, optlen);
+        ret = CC3000_EXPORT(setsockopt)(socket->fileno, SOL_SOCKET, SOCKOPT_RECV_NONBLOCK, &optval, optlen);
         if (ret == 0) {
-            ret = CC3000_EXPORT(setsockopt)(socket->u_state, SOL_SOCKET, SOCKOPT_ACCEPT_NONBLOCK, &optval, optlen);
+            ret = CC3000_EXPORT(setsockopt)(socket->fileno, SOL_SOCKET, SOCKOPT_ACCEPT_NONBLOCK, &optval, optlen);
         }
     } else {
         // set timeout
         socklen_t optlen = sizeof(timeout_ms);
-        ret = CC3000_EXPORT(setsockopt)(socket->u_state, SOL_SOCKET, SOCKOPT_RECV_TIMEOUT, &timeout_ms, optlen);
+        ret = CC3000_EXPORT(setsockopt)(socket->fileno, SOL_SOCKET, SOCKOPT_RECV_TIMEOUT, &timeout_ms, optlen);
     }
 
     if (ret != 0) {
@@ -363,7 +363,7 @@ STATIC int cc3k_socket_ioctl(mod_network_socket_obj_t *socket, mp_uint_t request
     if (request == MP_STREAM_POLL) {
         mp_uint_t flags = arg;
         ret = 0;
-        int fd = socket->u_state;
+        int fd = socket->fileno;
 
         // init fds
         fd_set rfds, wfds, xfds;
diff --git a/ports/stm32/modnwwiznet5k.c b/ports/stm32/modnwwiznet5k.c
index d3c2c516c3..f7adad3f31 100644
--- a/ports/stm32/modnwwiznet5k.c
+++ b/ports/stm32/modnwwiznet5k.c
@@ -99,33 +99,33 @@ STATIC int wiznet5k_gethostbyname(mp_obj_t nic, const char *name, mp_uint_t len,
 }
 
 STATIC int wiznet5k_socket_socket(mod_network_socket_obj_t *socket, int *_errno) {
-    if (socket->u_param.domain != MOD_NETWORK_AF_INET) {
+    if (socket->domain != MOD_NETWORK_AF_INET) {
         *_errno = MP_EAFNOSUPPORT;
         return -1;
     }
 
-    switch (socket->u_param.type) {
+    switch (socket->type) {
         case MOD_NETWORK_SOCK_STREAM:
-            socket->u_param.type = Sn_MR_TCP;
+            socket->type = Sn_MR_TCP;
             break;
         case MOD_NETWORK_SOCK_DGRAM:
-            socket->u_param.type = Sn_MR_UDP;
+            socket->type = Sn_MR_UDP;
             break;
         default:
             *_errno = MP_EINVAL;
             return -1;
     }
 
-    if (socket->u_param.fileno == -1) {
+    if (socket->fileno == -1) {
         // get first unused socket number
         for (mp_uint_t sn = 0; sn < _WIZCHIP_SOCK_NUM_; sn++) {
             if ((wiznet5k_obj.socket_used & (1 << sn)) == 0) {
                 wiznet5k_obj.socket_used |= (1 << sn);
-                socket->u_param.fileno = sn;
+                socket->fileno = sn;
                 break;
             }
         }
-        if (socket->u_param.fileno == -1) {
+        if (socket->fileno == -1) {
             // too many open sockets
             *_errno = MP_EMFILE;
             return -1;
@@ -137,13 +137,13 @@ STATIC int wiznet5k_socket_socket(mod_network_socket_obj_t *socket, int *_errno)
     // So, we defer the open until we know what kind of socket we want.
 
     // use "domain" to indicate that this socket has not yet been opened
-    socket->u_param.domain = 0;
+    socket->domain = 0;
 
     return 0;
 }
 
 STATIC void wiznet5k_socket_close(mod_network_socket_obj_t *socket) {
-    uint8_t sn = (uint8_t)socket->u_param.fileno;
+    uint8_t sn = (uint8_t)socket->fileno;
     if (sn < _WIZCHIP_SOCK_NUM_) {
         wiznet5k_obj.socket_used &= ~(1 << sn);
         WIZCHIP_EXPORT(close)(sn);
@@ -152,7 +152,7 @@ STATIC void wiznet5k_socket_close(mod_network_socket_obj_t *socket) {
 
 STATIC int wiznet5k_socket_bind(mod_network_socket_obj_t *socket, byte *ip, mp_uint_t port, int *_errno) {
     // open the socket in server mode (if port != 0)
-    mp_int_t ret = WIZCHIP_EXPORT(socket)(socket->u_param.fileno, socket->u_param.type, port, 0);
+    mp_int_t ret = WIZCHIP_EXPORT(socket)(socket->fileno, socket->type, port, 0);
     if (ret < 0) {
         wiznet5k_socket_close(socket);
         *_errno = -ret;
@@ -160,14 +160,14 @@ STATIC int wiznet5k_socket_bind(mod_network_socket_obj_t *socket, byte *ip, mp_u
     }
 
     // indicate that this socket has been opened
-    socket->u_param.domain = 1;
+    socket->domain = 1;
 
     // success
     return 0;
 }
 
 STATIC int wiznet5k_socket_listen(mod_network_socket_obj_t *socket, mp_int_t backlog, int *_errno) {
-    mp_int_t ret = WIZCHIP_EXPORT(listen)(socket->u_param.fileno);
+    mp_int_t ret = WIZCHIP_EXPORT(listen)(socket->fileno);
     if (ret < 0) {
         wiznet5k_socket_close(socket);
         *_errno = -ret;
@@ -178,17 +178,19 @@ STATIC int wiznet5k_socket_listen(mod_network_socket_obj_t *socket, mp_int_t bac
 
 STATIC int wiznet5k_socket_accept(mod_network_socket_obj_t *socket, mod_network_socket_obj_t *socket2, byte *ip, mp_uint_t *port, int *_errno) {
     for (;;) {
-        int sr = getSn_SR((uint8_t)socket->u_param.fileno);
+        int sr = getSn_SR((uint8_t)socket->fileno);
         if (sr == SOCK_ESTABLISHED) {
-            socket2->u_param = socket->u_param;
-            getSn_DIPR((uint8_t)socket2->u_param.fileno, ip);
-            *port = getSn_PORT(socket2->u_param.fileno);
+            socket2->domain = socket->domain;
+            socket2->type = socket->type;
+            socket2->fileno = socket->fileno;
+            getSn_DIPR((uint8_t)socket2->fileno, ip);
+            *port = getSn_PORT(socket2->fileno);
 
             // WIZnet turns the listening socket into the client socket, so we
             // need to re-bind and re-listen on another socket for the server.
             // TODO handle errors, especially no-more-sockets error
-            socket->u_param.domain = MOD_NETWORK_AF_INET;
-            socket->u_param.fileno = -1;
+            socket->domain = MOD_NETWORK_AF_INET;
+            socket->fileno = -1;
             int _errno2;
             if (wiznet5k_socket_socket(socket, &_errno2) != 0) {
                 // printf("(bad resocket %d)\n", _errno2);
@@ -217,7 +219,7 @@ STATIC int wiznet5k_socket_connect(mod_network_socket_obj_t *socket, byte *ip, m
 
     // now connect
     MP_THREAD_GIL_EXIT();
-    mp_int_t ret = WIZCHIP_EXPORT(connect)(socket->u_param.fileno, ip, port);
+    mp_int_t ret = WIZCHIP_EXPORT(connect)(socket->fileno, ip, port);
     MP_THREAD_GIL_ENTER();
 
     if (ret < 0) {
@@ -232,7 +234,7 @@ STATIC int wiznet5k_socket_connect(mod_network_socket_obj_t *socket, byte *ip, m
 
 STATIC mp_uint_t wiznet5k_socket_send(mod_network_socket_obj_t *socket, const byte *buf, mp_uint_t len, int *_errno) {
     MP_THREAD_GIL_EXIT();
-    mp_int_t ret = WIZCHIP_EXPORT(send)(socket->u_param.fileno, (byte *)buf, len);
+    mp_int_t ret = WIZCHIP_EXPORT(send)(socket->fileno, (byte *)buf, len);
     MP_THREAD_GIL_ENTER();
 
     // TODO convert Wiz errno's to POSIX ones
@@ -246,7 +248,7 @@ STATIC mp_uint_t wiznet5k_socket_send(mod_network_socket_obj_t *socket, const by
 
 STATIC mp_uint_t wiznet5k_socket_recv(mod_network_socket_obj_t *socket, byte *buf, mp_uint_t len, int *_errno) {
     MP_THREAD_GIL_EXIT();
-    mp_int_t ret = WIZCHIP_EXPORT(recv)(socket->u_param.fileno, buf, len);
+    mp_int_t ret = WIZCHIP_EXPORT(recv)(socket->fileno, buf, len);
     MP_THREAD_GIL_ENTER();
 
     // TODO convert Wiz errno's to POSIX ones
@@ -259,7 +261,7 @@ STATIC mp_uint_t wiznet5k_socket_recv(mod_network_socket_obj_t *socket, byte *bu
 }
 
 STATIC mp_uint_t wiznet5k_socket_sendto(mod_network_socket_obj_t *socket, const byte *buf, mp_uint_t len, byte *ip, mp_uint_t port, int *_errno) {
-    if (socket->u_param.domain == 0) {
+    if (socket->domain == 0) {
         // socket not opened; use "bind" function to open the socket in client mode
         if (wiznet5k_socket_bind(socket, ip, 0, _errno) != 0) {
             return -1;
@@ -267,7 +269,7 @@ STATIC mp_uint_t wiznet5k_socket_sendto(mod_network_socket_obj_t *socket, const
     }
 
     MP_THREAD_GIL_EXIT();
-    mp_int_t ret = WIZCHIP_EXPORT(sendto)(socket->u_param.fileno, (byte *)buf, len, ip, port);
+    mp_int_t ret = WIZCHIP_EXPORT(sendto)(socket->fileno, (byte *)buf, len, ip, port);
     MP_THREAD_GIL_ENTER();
 
     if (ret < 0) {
@@ -281,7 +283,7 @@ STATIC mp_uint_t wiznet5k_socket_sendto(mod_network_socket_obj_t *socket, const
 STATIC mp_uint_t wiznet5k_socket_recvfrom(mod_network_socket_obj_t *socket, byte *buf, mp_uint_t len, byte *ip, mp_uint_t *port, int *_errno) {
     uint16_t port2;
     MP_THREAD_GIL_EXIT();
-    mp_int_t ret = WIZCHIP_EXPORT(recvfrom)(socket->u_param.fileno, buf, len, ip, &port2);
+    mp_int_t ret = WIZCHIP_EXPORT(recvfrom)(socket->fileno, buf, len, ip, &port2);
     MP_THREAD_GIL_ENTER();
     *port = port2;
     if (ret < 0) {
@@ -307,7 +309,7 @@ STATIC int wiznet5k_socket_settimeout(mod_network_socket_obj_t *socket, mp_uint_
     if (timeout_ms == 0) {
         // set non-blocking mode
         uint8_t arg = SOCK_IO_NONBLOCK;
-        WIZCHIP_EXPORT(ctlsocket)(socket->u_param.fileno, CS_SET_IOMODE, &arg);
+        WIZCHIP_EXPORT(ctlsocket)(socket->fileno, CS_SET_IOMODE, &arg);
     }
     */
 }
@@ -315,10 +317,10 @@ STATIC int wiznet5k_socket_settimeout(mod_network_socket_obj_t *socket, mp_uint_
 STATIC int wiznet5k_socket_ioctl(mod_network_socket_obj_t *socket, mp_uint_t request, mp_uint_t arg, int *_errno) {
     if (request == MP_STREAM_POLL) {
         int ret = 0;
-        if (arg & MP_STREAM_POLL_RD && getSn_RX_RSR(socket->u_param.fileno) != 0) {
+        if (arg & MP_STREAM_POLL_RD && getSn_RX_RSR(socket->fileno) != 0) {
             ret |= MP_STREAM_POLL_RD;
         }
-        if (arg & MP_STREAM_POLL_WR && getSn_TX_FSR(socket->u_param.fileno) != 0) {
+        if (arg & MP_STREAM_POLL_WR && getSn_TX_FSR(socket->fileno) != 0) {
             ret |= MP_STREAM_POLL_WR;
         }
         return ret;