diff --git a/CHANGELOG b/CHANGELOG
index cb961dd3..28d8cbcb 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -117,6 +117,9 @@ HISTORY
 
   ++ Bugfixes:
 
+  2014-09-02: Simon Goldschmidt
+  * sockets.c: fixed bug #42117 lwip_fcntl does not set errno
+
   2014-09-02: Simon Goldschmidt
   * tcp.c: fixed bug #42299 tcp_abort() leaves freed pcb on tcp_bound_pcbs list
 
diff --git a/src/api/sockets.c b/src/api/sockets.c
index 19edfc57..cbdb4009 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -2622,23 +2622,28 @@ lwip_fcntl(int s, int cmd, int val)
   struct lwip_sock *sock = get_socket(s);
   int ret = -1;
 
-  if (!sock || !sock->conn) {
+  if (!sock) {
     return -1;
   }
 
   switch (cmd) {
   case F_GETFL:
     ret = netconn_is_nonblocking(sock->conn) ? O_NONBLOCK : 0;
+    sock_set_errno(sock, 0);
     break;
   case F_SETFL:
     if ((val & ~O_NONBLOCK) == 0) {
       /* only O_NONBLOCK, all other bits are zero */
       netconn_set_nonblocking(sock->conn, val & O_NONBLOCK);
       ret = 0;
+      sock_set_errno(sock, 0);
+    } else {
+      sock_set_errno(sock, ENOSYS); /* not yet implemented */
     }
     break;
   default:
     LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_fcntl(%d, UNIMPL: %d, %d)\n", s, cmd, val));
+    sock_set_errno(sock, ENOSYS); /* not yet implemented */
     break;
   }
   return ret;