diff --git a/src/api/sockets.c b/src/api/sockets.c
index 8e33b416..95b8b7e4 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -217,7 +217,7 @@ struct lwip_sock {
   /** error happened for this socket, set by event_callback(), tested by select */
   u16_t errevent;
   /** last error that occurred on this socket */
-  int err;
+  lwip_sockerr_t err;
   /** counter of how many threads are waiting for this socket using select */
   SELWAIT_T select_waiting;
 };
@@ -295,7 +295,7 @@ static volatile int select_cb_ctr;
 
 #define sock_set_errno(sk, e) do { \
   const int sockerr = (e); \
-  sk->err = sockerr; \
+  sk->err = (lwip_sockerr_t)sockerr; \
   set_errno(sockerr); \
 } while (0)
 
@@ -305,8 +305,8 @@ static void event_callback(struct netconn *conn, enum netconn_evt evt, u16_t len
 static void lwip_getsockopt_callback(void *arg);
 static void lwip_setsockopt_callback(void *arg);
 #endif
-static int lwip_getsockopt_impl(int s, int level, int optname, void *optval, socklen_t *optlen);
-static int lwip_setsockopt_impl(int s, int level, int optname, const void *optval, socklen_t optlen);
+static lwip_sockerr_t lwip_getsockopt_impl(int s, int level, int optname, void *optval, socklen_t *optlen);
+static lwip_sockerr_t lwip_setsockopt_impl(int s, int level, int optname, const void *optval, socklen_t optlen);
 
 #if LWIP_IPV4 && LWIP_IPV6
 static void
@@ -1780,7 +1780,7 @@ lwip_getsockname(int s, struct sockaddr *name, socklen_t *namelen)
 int
 lwip_getsockopt(int s, int level, int optname, void *optval, socklen_t *optlen)
 {
-  int err;
+  lwip_sockerr_t err;
   struct lwip_sock *sock = get_socket(s);
 #if !LWIP_TCPIP_CORE_LOCKING
   err_t cberr;
@@ -1876,10 +1876,10 @@ lwip_getsockopt_callback(void *arg)
 /** lwip_getsockopt_impl: the actual implementation of getsockopt:
  * same argument as lwip_getsockopt, either called directly or through callback
  */
-static int
+static lwip_sockerr_t
 lwip_getsockopt_impl(int s, int level, int optname, void *optval, socklen_t *optlen)
 {
-  int err = 0;
+  lwip_sockerr_t err = 0;
   struct lwip_sock *sock = tryget_socket(s);
   if (!sock) {
     return EBADF;
@@ -2187,7 +2187,7 @@ lwip_getsockopt_impl(int s, int level, int optname, void *optval, socklen_t *opt
 int
 lwip_setsockopt(int s, int level, int optname, const void *optval, socklen_t optlen)
 {
-  int err = 0;
+  lwip_sockerr_t err = 0;
   struct lwip_sock *sock = get_socket(s);
 #if !LWIP_TCPIP_CORE_LOCKING
   err_t cberr;
@@ -2278,10 +2278,10 @@ lwip_setsockopt_callback(void *arg)
 /** lwip_setsockopt_impl: the actual implementation of setsockopt:
  * same argument as lwip_setsockopt, either called directly or through callback
  */
-static int
+static lwip_sockerr_t
 lwip_setsockopt_impl(int s, int level, int optname, const void *optval, socklen_t optlen)
 {
-  int err = 0;
+  lwip_sockerr_t err = 0;
   struct lwip_sock *sock = tryget_socket(s);
   if (!sock) {
     return EBADF;
diff --git a/src/include/lwip/priv/sockets_priv.h b/src/include/lwip/priv/sockets_priv.h
index 3e226cbb..94680c3b 100644
--- a/src/include/lwip/priv/sockets_priv.h
+++ b/src/include/lwip/priv/sockets_priv.h
@@ -48,6 +48,19 @@
 extern "C" {
 #endif
 
+/** Define LWIP_SOCKERR_T in cc.h if you want to use a different type for your
+ *  platform (must be signed and big enough to hold all error constants). */
+#ifdef LWIP_SOCKERR_T
+typedef LWIP_SOCKERR_T lwip_sockerr_t;
+#else /* LWIP_SOCKERR_T */
+#ifdef LWIP_PROVIDE_ERRNO
+/* we only use our own error constants, 8 bits are enough */
+typedef s8_t lwip_sockerr_t;
+#else
+typedef int lwip_sockerr_t;
+#endif
+#endif /* LWIP_SOCKERR_T*/
+
 #if LWIP_SOCKET_SET_ERRNO
 #ifndef set_errno
 #define set_errno(err) do { if (err) { errno = (err); } } while(0)
@@ -82,7 +95,7 @@ struct lwip_setgetsockopt_data {
   /** size of *optval */
   socklen_t optlen;
   /** if an error occurs, it is temporarily stored here */
-  int err;
+  lwip_sockerr_t err;
   /** semaphore to wake up the calling task */
   void* completed_sem;
 };