diff --git a/net/slirp.c b/net/slirp.c
index 9fbc949..01ed21c 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -91,15 +91,15 @@
     QTAILQ_HEAD_INITIALIZER(slirp_stacks);
 
 static int slirp_hostfwd(SlirpState *s, const char *redir_str,
-                         int legacy_format);
+                         int legacy_format, Error **errp);
 static int slirp_guestfwd(SlirpState *s, const char *config_str,
-                          int legacy_format);
+                          int legacy_format, Error **errp);
 
 #ifndef _WIN32
 static const char *legacy_smb_export;
 
 static int slirp_smb(SlirpState *s, const char *exported_dir,
-                     struct in_addr vserver_addr);
+                     struct in_addr vserver_addr, Error **errp);
 static void slirp_smb_cleanup(SlirpState *s);
 #else
 static inline void slirp_smb_cleanup(SlirpState *s) { }
@@ -155,7 +155,7 @@
                           const char *bootfile, const char *vdhcp_start,
                           const char *vnameserver, const char *vnameserver6,
                           const char *smb_export, const char *vsmbserver,
-                          const char **dnssearch)
+                          const char **dnssearch, Error **errp)
 {
     /* default settings according to historic slirp */
     struct in_addr net  = { .s_addr = htonl(0x0a000200) }; /* 10.0.2.0 */
@@ -178,15 +178,18 @@
     struct slirp_config_str *config;
 
     if (!ipv4 && (vnetwork || vhost || vnameserver)) {
+        error_setg(errp, "IPv4 disabled but netmask/host/dns provided");
         return -1;
     }
 
     if (!ipv6 && (vprefix6 || vhost6 || vnameserver6)) {
+        error_setg(errp, "IPv6 disabled but prefix/host6/dns6 provided");
         return -1;
     }
 
     if (!ipv4 && !ipv6) {
         /* It doesn't make sense to disable both */
+        error_setg(errp, "IPv4 and IPv6 disabled");
         return -1;
     }
 
@@ -200,6 +203,7 @@
     if (vnetwork) {
         if (get_str_sep(buf, sizeof(buf), &vnetwork, '/') < 0) {
             if (!inet_aton(vnetwork, &net)) {
+                error_setg(errp, "Failed to parse netmask");
                 return -1;
             }
             addr = ntohl(net.s_addr);
@@ -220,14 +224,19 @@
             }
         } else {
             if (!inet_aton(buf, &net)) {
+                error_setg(errp, "Failed to parse netmask");
                 return -1;
             }
             shift = strtol(vnetwork, &end, 10);
             if (*end != '\0') {
                 if (!inet_aton(vnetwork, &mask)) {
+                    error_setg(errp,
+                               "Failed to parse netmask (trailing chars)");
                     return -1;
                 }
             } else if (shift < 4 || shift > 32) {
+                error_setg(errp,
+                           "Invalid netmask provided (must be in range 4-32)");
                 return -1;
             } else {
                 mask.s_addr = htonl(0xffffffff << (32 - shift));
@@ -240,30 +249,43 @@
     }
 
     if (vhost && !inet_aton(vhost, &host)) {
+        error_setg(errp, "Failed to parse host");
         return -1;
     }
     if ((host.s_addr & mask.s_addr) != net.s_addr) {
+        error_setg(errp, "Host doesn't belong to network");
         return -1;
     }
 
     if (vnameserver && !inet_aton(vnameserver, &dns)) {
+        error_setg(errp, "Failed to parse DNS");
         return -1;
     }
-    if ((dns.s_addr & mask.s_addr) != net.s_addr ||
-        dns.s_addr == host.s_addr) {
+    if ((dns.s_addr & mask.s_addr) != net.s_addr) {
+        error_setg(errp, "DNS doesn't belong to network");
+        return -1;
+    }
+    if (dns.s_addr == host.s_addr) {
+        error_setg(errp, "DNS must be different from host");
         return -1;
     }
 
     if (vdhcp_start && !inet_aton(vdhcp_start, &dhcp)) {
+        error_setg(errp, "Failed to parse DHCP start address");
         return -1;
     }
-    if ((dhcp.s_addr & mask.s_addr) != net.s_addr ||
-        dhcp.s_addr == host.s_addr || dhcp.s_addr == dns.s_addr) {
+    if ((dhcp.s_addr & mask.s_addr) != net.s_addr) {
+        error_setg(errp, "DHCP doesn't belong to network");
+        return -1;
+    }
+    if (dhcp.s_addr == host.s_addr || dhcp.s_addr == dns.s_addr) {
+        error_setg(errp, "DNS must be different from host and DNS");
         return -1;
     }
 
 #ifndef _WIN32
     if (vsmbserver && !inet_aton(vsmbserver, &smbsrv)) {
+        error_setg(errp, "Failed to parse SMB address");
         return -1;
     }
 #endif
@@ -272,6 +294,7 @@
     /* No inet_pton helper before Vista... */
     if (vprefix6) {
         /* Unsupported */
+        error_setg(errp, "IPv6 prefix not supported");
         return -1;
     }
     memset(&ip6_prefix, 0, sizeof(ip6_prefix));
@@ -282,6 +305,7 @@
         vprefix6 = "fec0::";
     }
     if (!inet_pton(AF_INET6, vprefix6, &ip6_prefix)) {
+        error_setg(errp, "Failed to parse IPv6 prefix");
         return -1;
     }
 #endif
@@ -290,17 +314,22 @@
         vprefix6_len = 64;
     }
     if (vprefix6_len < 0 || vprefix6_len > 126) {
+        error_setg(errp,
+                   "Invalid prefix provided (prefix len must be in range 0-126");
         return -1;
     }
 
     if (vhost6) {
 #if defined(_WIN32) && (_WIN32_WINNT < 0x0600)
+        error_setg(errp, "IPv6 host not supported");
         return -1;
 #else
         if (!inet_pton(AF_INET6, vhost6, &ip6_host)) {
+            error_setg(errp, "Failed to parse IPv6 host");
             return -1;
         }
         if (!in6_equal_net(&ip6_prefix, &ip6_host, vprefix6_len)) {
+            error_setg(errp, "IPv6 Host doesn't belong to network");
             return -1;
         }
 #endif
@@ -311,12 +340,15 @@
 
     if (vnameserver6) {
 #if defined(_WIN32) && (_WIN32_WINNT < 0x0600)
+        error_setg(errp, "IPv6 DNS not supported");
         return -1;
 #else
         if (!inet_pton(AF_INET6, vnameserver6, &ip6_dns)) {
+            error_setg(errp, "Failed to parse IPv6 DNS");
             return -1;
         }
         if (!in6_equal_net(&ip6_prefix, &ip6_dns, vprefix6_len)) {
+            error_setg(errp, "IPv6 DNS doesn't belong to network");
             return -1;
         }
 #endif
@@ -343,12 +375,14 @@
     for (config = slirp_configs; config; config = config->next) {
         if (config->flags & SLIRP_CFG_HOSTFWD) {
             if (slirp_hostfwd(s, config->str,
-                              config->flags & SLIRP_CFG_LEGACY) < 0)
+                              config->flags & SLIRP_CFG_LEGACY, errp) < 0) {
                 goto error;
+            }
         } else {
             if (slirp_guestfwd(s, config->str,
-                               config->flags & SLIRP_CFG_LEGACY) < 0)
+                               config->flags & SLIRP_CFG_LEGACY, errp) < 0) {
                 goto error;
+            }
         }
     }
 #ifndef _WIN32
@@ -356,8 +390,9 @@
         smb_export = legacy_smb_export;
     }
     if (smb_export) {
-        if (slirp_smb(s, smb_export, smbsrv) < 0)
+        if (slirp_smb(s, smb_export, smbsrv, errp) < 0) {
             goto error;
+        }
     }
 #endif
 
@@ -452,7 +487,7 @@
 }
 
 static int slirp_hostfwd(SlirpState *s, const char *redir_str,
-                         int legacy_format)
+                         int legacy_format, Error **errp)
 {
     struct in_addr host_addr = { .s_addr = INADDR_ANY };
     struct in_addr guest_addr = { .s_addr = 0 };
@@ -505,14 +540,14 @@
 
     if (slirp_add_hostfwd(s->slirp, is_udp, host_addr, host_port, guest_addr,
                           guest_port) < 0) {
-        error_report("could not set up host forwarding rule '%s'",
-                     redir_str);
+        error_setg(errp, "Could not set up host forwarding rule '%s'",
+                   redir_str);
         return -1;
     }
     return 0;
 
  fail_syntax:
-    error_report("invalid host forwarding rule '%s'", redir_str);
+    error_setg(errp, "Invalid host forwarding rule '%s'", redir_str);
     return -1;
 }
 
@@ -532,7 +567,10 @@
         redir_str = arg1;
     }
     if (s) {
-        slirp_hostfwd(s, redir_str, 0);
+        Error *err = NULL;
+        if (slirp_hostfwd(s, redir_str, 0, &err) < 0) {
+            error_report_err(err);
+        }
     }
 
 }
@@ -540,6 +578,8 @@
 int net_slirp_redir(const char *redir_str)
 {
     struct slirp_config_str *config;
+    Error *err = NULL;
+    int res;
 
     if (QTAILQ_EMPTY(&slirp_stacks)) {
         config = g_malloc(sizeof(*config));
@@ -550,7 +590,11 @@
         return 0;
     }
 
-    return slirp_hostfwd(QTAILQ_FIRST(&slirp_stacks), redir_str, 1);
+    res = slirp_hostfwd(QTAILQ_FIRST(&slirp_stacks), redir_str, 1, &err);
+    if (res < 0) {
+        error_report_err(err);
+    }
+    return res;
 }
 
 #ifndef _WIN32
@@ -576,7 +620,7 @@
 }
 
 static int slirp_smb(SlirpState* s, const char *exported_dir,
-                     struct in_addr vserver_addr)
+                     struct in_addr vserver_addr, Error **errp)
 {
     char *smb_conf;
     char *smb_cmdline;
@@ -585,25 +629,25 @@
 
     passwd = getpwuid(geteuid());
     if (!passwd) {
-        error_report("failed to retrieve user name");
+        error_setg(errp, "Failed to retrieve user name");
         return -1;
     }
 
     if (access(CONFIG_SMBD_COMMAND, F_OK)) {
-        error_report("could not find '%s', please install it",
-                     CONFIG_SMBD_COMMAND);
+        error_setg(errp, "Could not find '%s', please install it",
+                   CONFIG_SMBD_COMMAND);
         return -1;
     }
 
     if (access(exported_dir, R_OK | X_OK)) {
-        error_report("error accessing shared directory '%s': %s",
-                     exported_dir, strerror(errno));
+        error_setg(errp, "Error accessing shared directory '%s': %s",
+                   exported_dir, strerror(errno));
         return -1;
     }
 
     s->smb_dir = g_dir_make_tmp("qemu-smb.XXXXXX", NULL);
     if (!s->smb_dir) {
-        error_report("could not create samba server dir");
+        error_setg(errp, "Could not create samba server dir");
         return -1;
     }
     smb_conf = g_strdup_printf("%s/%s", s->smb_dir, "smb.conf");
@@ -611,8 +655,9 @@
     f = fopen(smb_conf, "w");
     if (!f) {
         slirp_smb_cleanup(s);
-        error_report("could not create samba server configuration file '%s'",
-                     smb_conf);
+        error_setg(errp,
+                   "Could not create samba server configuration file '%s'",
+                    smb_conf);
         g_free(smb_conf);
         return -1;
     }
@@ -660,7 +705,7 @@
         slirp_add_exec(s->slirp, 0, smb_cmdline, &vserver_addr, 445) < 0) {
         slirp_smb_cleanup(s);
         g_free(smb_cmdline);
-        error_report("conflicting/invalid smbserver address");
+        error_setg(errp, "Conflicting/invalid smbserver address");
         return -1;
     }
     g_free(smb_cmdline);
@@ -678,8 +723,13 @@
     }
     legacy_smb_export = exported_dir;
     if (!QTAILQ_EMPTY(&slirp_stacks)) {
-        return slirp_smb(QTAILQ_FIRST(&slirp_stacks), exported_dir,
-                         vserver_addr);
+        Error *err = NULL;
+        int res = slirp_smb(QTAILQ_FIRST(&slirp_stacks), exported_dir,
+                            vserver_addr, &err);
+        if (res < 0) {
+            error_report_err(err);
+        }
+        return res;
     }
     return 0;
 }
@@ -706,7 +756,7 @@
 }
 
 static int slirp_guestfwd(SlirpState *s, const char *config_str,
-                          int legacy_format)
+                          int legacy_format, Error **errp)
 {
     struct in_addr server = { .s_addr = 0 };
     struct GuestFwd *fwd;
@@ -746,8 +796,8 @@
 
     if ((strlen(p) > 4) && !strncmp(p, "cmd:", 4)) {
         if (slirp_add_exec(s->slirp, 0, &p[4], &server, port) < 0) {
-            error_report("conflicting/invalid host:port in guest forwarding "
-                         "rule '%s'", config_str);
+            error_setg(errp, "Conflicting/invalid host:port in guest "
+                       "forwarding rule '%s'", config_str);
             return -1;
         }
     } else {
@@ -755,21 +805,22 @@
         Chardev *chr = qemu_chr_new(buf, p);
 
         if (!chr) {
-            error_report("could not open guest forwarding device '%s'", buf);
+            error_setg(errp, "Could not open guest forwarding device '%s'",
+                       buf);
             return -1;
         }
 
         fwd = g_new(struct GuestFwd, 1);
         qemu_chr_fe_init(&fwd->hd, chr, &err);
         if (err) {
-            error_report_err(err);
+            error_propagate(errp, err);
             g_free(fwd);
             return -1;
         }
 
         if (slirp_add_exec(s->slirp, 3, &fwd->hd, &server, port) < 0) {
-            error_report("conflicting/invalid host:port in guest forwarding "
-                         "rule '%s'", config_str);
+            error_setg(errp, "Conflicting/invalid host:port in guest "
+                       "forwarding rule '%s'", config_str);
             g_free(fwd);
             return -1;
         }
@@ -783,7 +834,7 @@
     return 0;
 
  fail_syntax:
-    error_report("invalid guest forwarding rule '%s'", config_str);
+    error_setg(errp, "Invalid guest forwarding rule '%s'", config_str);
     return -1;
 }
 
@@ -845,7 +896,6 @@
 int net_init_slirp(const Netdev *netdev, const char *name,
                    NetClientState *peer, Error **errp)
 {
-    /* FIXME error_setg(errp, ...) on failure */
     struct slirp_config_str *config;
     char *vnet;
     int ret;
@@ -882,7 +932,7 @@
                          user->ipv6_host, user->hostname, user->tftp,
                          user->bootfile, user->dhcpstart,
                          user->dns, user->ipv6_dns, user->smb,
-                         user->smbserver, dnssearch);
+                         user->smbserver, dnssearch, errp);
 
     while (slirp_configs) {
         config = slirp_configs;
@@ -919,7 +969,11 @@
         slirp_configs = config;
         *ret = 0;
     } else {
-        *ret = slirp_guestfwd(QTAILQ_FIRST(&slirp_stacks), optarg, 1);
+        Error *err = NULL;
+        *ret = slirp_guestfwd(QTAILQ_FIRST(&slirp_stacks), optarg, 1, &err);
+        if (*ret < 0) {
+            error_report_err(err);
+        }
     }
 
     return 1;