diff --git a/sim_sock.c b/sim_sock.c
index 01b25293..428a19aa 100644
--- a/sim_sock.c
+++ b/sim_sock.c
@@ -917,7 +917,7 @@ if (sta == SOCKET_ERROR)                                /* bind error? */
 if (!(opt_flags & SIM_SOCK_OPT_BLOCKING)) {
     sta = sim_setnonblock (newsock);                    /* set nonblocking */
     if (sta == SOCKET_ERROR)                            /* fcntl error? */
-        return sim_err_sock (newsock, "fcntl");
+        return sim_err_sock (newsock, "setnonblock");
     }
 sta = listen (newsock, 1);                              /* listen on socket */
 if (sta == SOCKET_ERROR)                                /* listen error? */
@@ -989,7 +989,7 @@ if (!(opt_flags & SIM_SOCK_OPT_BLOCKING)) {
     sta = sim_setnonblock (newsock);                    /* set nonblocking */
     if (sta == SOCKET_ERROR) {                          /* fcntl error? */
         p_freeaddrinfo (result);
-        return sim_err_sock (newsock, "fcntl");
+        return sim_err_sock (newsock, "setnonblock");
         }
     }
 if ((!(opt_flags & SIM_SOCK_OPT_DATAGRAM)) && (opt_flags & SIM_SOCK_OPT_NODELAY)) {
@@ -1007,6 +1007,11 @@ if (!(opt_flags & SIM_SOCK_OPT_DATAGRAM)) {
     if (sta == -1) 
         return sim_err_sock (newsock, "setsockopt KEEPALIVE");
     }
+if (!(opt_flags & SIM_SOCK_OPT_BLOCKING)) {
+    sta = sim_setnonblock (newsock);                    /* set nonblocking */
+    if (sta == SOCKET_ERROR)                            /* fcntl error? */
+        return sim_err_sock (newsock, "setnonblock");
+    }
 sta = connect (newsock, result->ai_addr, result->ai_addrlen);
 p_freeaddrinfo (result);
 if (sta == SOCKET_ERROR) {
@@ -1076,7 +1081,7 @@ if (connectaddr != NULL) {
 if (!(opt_flags & SIM_SOCK_OPT_BLOCKING)) {
     sta = sim_setnonblock (newsock);                    /* set nonblocking */
     if (sta == SOCKET_ERROR)                            /* fcntl error? */
-        return sim_err_sock (newsock, "fcntl");
+        return sim_err_sock (newsock, "setnonblock");
     }
 
 if ((opt_flags & SIM_SOCK_OPT_NODELAY)) {
diff --git a/sim_sock.h b/sim_sock.h
index 6cf43650..f42e8f16 100644
--- a/sim_sock.h
+++ b/sim_sock.h
@@ -120,7 +120,7 @@ int sim_parse_addr_ex (const char *cptr, char *host, size_t hostlen, const char
 SOCKET sim_master_sock_ex (const char *hostport, int *parse_status, int opt_flags);
 #define sim_master_sock(hostport, parse_status) sim_master_sock_ex(hostport, parse_status, ((sim_switches & SWMASK ('U')) ? SIM_SOCK_OPT_REUSEADDR : 0))
 SOCKET sim_connect_sock_ex (const char *sourcehostport, const char *hostport, const char *default_host, const char *default_port, int opt_flags);
-#define sim_connect_sock(hostport, default_host, default_port) sim_connect_sock_ex(NULL, hostport, default_host, default_port, 0)
+#define sim_connect_sock(hostport, default_host, default_port) sim_connect_sock_ex(NULL, hostport, default_host, default_port, SIM_SOCK_OPT_BLOCKING)
 SOCKET sim_accept_conn_ex (SOCKET master, char **connectaddr, int opt_flags);
 #define sim_accept_conn(master, connectaddr) sim_accept_conn_ex(master, connectaddr, 0)
 int sim_check_conn (SOCKET sock, int rd);
diff --git a/sim_tmxr.c b/sim_tmxr.c
index 710cf14f..2c3796b0 100644
--- a/sim_tmxr.c
+++ b/sim_tmxr.c
@@ -1284,7 +1284,9 @@ for (i = 0; i < mp->lines; i++) {                       /* check each line in se
         (!lp->modem_control || (lp->modembits & TMXR_MDM_DTR))) {
         snprintf (msg, sizeof (msg) - 1, "tmxr_poll_conn() - establishing outgoing connection to: %s", lp->destination);
         tmxr_debug_connect_line (lp, msg);
-        lp->connecting = sim_connect_sock_ex (lp->datagram ? lp->port : NULL, lp->destination, "localhost", NULL, (lp->datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | (lp->mp->packet ? SIM_SOCK_OPT_NODELAY : 0));
+        lp->connecting = sim_connect_sock_ex (lp->datagram ? lp->port : NULL, lp->destination, "localhost", NULL, (lp->datagram ? SIM_SOCK_OPT_DATAGRAM : 0)  | 
+                                                                                                                  (lp->mp->packet ? SIM_SOCK_OPT_NODELAY : 0) | 
+                                                                                                                  SIM_SOCK_OPT_BLOCKING);
         }
 
     }
@@ -1354,7 +1356,9 @@ if ((lp->destination) && (!lp->serport)) {
     if ((!lp->modem_control) || (lp->modembits & TMXR_MDM_DTR)) {
         sprintf (msg, "tmxr_reset_ln_ex() - connecting to %s", lp->destination);
         tmxr_debug_connect_line (lp, msg);
-        lp->connecting = sim_connect_sock_ex (lp->datagram ? lp->port : NULL, lp->destination, "localhost", NULL, (lp->datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | (lp->packet ? SIM_SOCK_OPT_NODELAY : 0));
+        lp->connecting = sim_connect_sock_ex (lp->datagram ? lp->port : NULL, lp->destination, "localhost", NULL, (lp->datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | 
+                                                                                                                  (lp->packet ? SIM_SOCK_OPT_NODELAY : 0)    | 
+                                                                                                                  SIM_SOCK_OPT_BLOCKING);
         }
     }
 tmxr_init_line (lp);                                /* initialize line state */
@@ -1644,7 +1648,9 @@ if (lp->mp && lp->modem_control) {                  /* This API ONLY works on mo
 
                 sprintf (msg, "tmxr_set_get_modem_bits() - establishing outgoing connection to: %s", lp->destination);
                 tmxr_debug_connect_line (lp, msg);
-                lp->connecting = sim_connect_sock_ex (lp->datagram ? lp->port : NULL, lp->destination, "localhost", NULL, (lp->datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | (lp->packet ? SIM_SOCK_OPT_NODELAY : 0));
+                lp->connecting = sim_connect_sock_ex (lp->datagram ? lp->port : NULL, lp->destination, "localhost", NULL, (lp->datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | 
+                                                                                                                          (lp->packet ? SIM_SOCK_OPT_NODELAY : 0)    |
+                                                                                                                          SIM_SOCK_OPT_BLOCKING);
                 }
             }
         }
@@ -2799,7 +2805,9 @@ while (*tptr) {
                     else
                         return sim_messagef (SCPE_ARG, "Unexpected specifier: %s\n", eptr);
                 }
-            sock = sim_connect_sock_ex (NULL, hostport, "localhost", NULL, (datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | (packet ? SIM_SOCK_OPT_NODELAY : 0));
+            sock = sim_connect_sock_ex (NULL, hostport, "localhost", NULL, (datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | 
+                                                                           (packet ? SIM_SOCK_OPT_NODELAY : 0)    |
+                                                                           SIM_SOCK_OPT_BLOCKING);
             if (sock != INVALID_SOCKET)
                 sim_close_sock (sock);
             else
@@ -2951,7 +2959,9 @@ while (*tptr) {
                         return sim_messagef (SCPE_ARG, "Missing listen port for Datagram socket\n");
                     }
                 lp->packet = packet;
-                sock = sim_connect_sock_ex (datagram ? listen : NULL, hostport, "localhost", NULL, (datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | (packet ? SIM_SOCK_OPT_NODELAY : 0));
+                sock = sim_connect_sock_ex (datagram ? listen : NULL, hostport, "localhost", NULL, (datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | 
+                                                                                                   (packet ? SIM_SOCK_OPT_NODELAY : 0)    | 
+                                                                                                   SIM_SOCK_OPT_BLOCKING);
                 if (sock != INVALID_SOCKET) {
                     _mux_detach_line (lp, FALSE, TRUE);
                     lp->destination = (char *)malloc(1+strlen(hostport));
@@ -3066,7 +3076,9 @@ while (*tptr) {
                     else
                         return sim_messagef (SCPE_ARG, "Missing listen port for Datagram socket\n");
                     }
-                sock = sim_connect_sock_ex (datagram ? listen : NULL, hostport, "localhost", NULL, (datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | (packet ? SIM_SOCK_OPT_NODELAY : 0));
+                sock = sim_connect_sock_ex (datagram ? listen : NULL, hostport, "localhost", NULL, (datagram ? SIM_SOCK_OPT_DATAGRAM : 0) | 
+                                                                                                   (packet ? SIM_SOCK_OPT_NODELAY : 0)    | 
+                                                                                                   SIM_SOCK_OPT_BLOCKING);
                 if (sock != INVALID_SOCKET) {
                     _mux_detach_line (lp, FALSE, TRUE);
                     lp->destination = (char *)malloc(1+strlen(hostport));
diff --git a/slirp_glue/sim_slirp.c b/slirp_glue/sim_slirp.c
index fe83f70b..9971d2a6 100644
--- a/slirp_glue/sim_slirp.c
+++ b/slirp_glue/sim_slirp.c
@@ -344,7 +344,7 @@ else {
         if ((rnd_val & 0xFFFF) == 0)
             ++rnd_val;
         sprintf (db_host, "localhost:%d", (int)(rnd_val & 0xFFFF));
-        slirp->db_chime  = sim_connect_sock_ex (db_host, db_host, NULL, NULL, SIM_SOCK_OPT_DATAGRAM);
+        slirp->db_chime  = sim_connect_sock_ex (db_host, db_host, NULL, NULL, SIM_SOCK_OPT_DATAGRAM | SIM_SOCK_OPT_BLOCKING);
         } while (slirp->db_chime == INVALID_SOCKET);
     memset (&pfd, 0, sizeof (pfd));
     pfd.fd = slirp->db_chime;