void qemu_purge_queued_packets(NetClientState *nc);
 void qemu_flush_queued_packets(NetClientState *nc);
 void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge);
-void qemu_set_info_str(NetClientState *nc, const char *fmt, ...);
+void qemu_set_info_str(NetClientState *nc,
+                       const char *fmt, ...) G_GNUC_PRINTF(2, 3);
 void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6]);
 bool qemu_has_ufo(NetClientState *nc);
 bool qemu_has_vnet_hdr(NetClientState *nc);
 
         s->fd = -1;
         net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
         s->nc.link_down = true;
-        qemu_set_info_str(&s->nc, "");
+        qemu_set_info_str(&s->nc, "%s", "");
 
         return;
     }
 
 
         net_socket_rs_init(&s->rs, net_stream_rs_finalize, false);
         s->nc.link_down = true;
-        qemu_set_info_str(&s->nc, "");
+        qemu_set_info_str(&s->nc, "%s", "");
 
         qapi_event_send_netdev_stream_disconnected(s->nc.name);
 
     }
     g_assert(addr != NULL);
     uri = socket_uri(addr);
-    qemu_set_info_str(&s->nc, uri);
+    qemu_set_info_str(&s->nc, "%s", uri);
     g_free(uri);
     qapi_event_send_netdev_stream_connected(s->nc.name, addr);
     qapi_free_SocketAddress(addr);
     addr = qio_channel_socket_get_remote_address(sioc, NULL);
     g_assert(addr != NULL);
     uri = socket_uri(addr);
-    qemu_set_info_str(&s->nc, uri);
+    qemu_set_info_str(&s->nc, "%s", uri);
     g_free(uri);
 
     ret = qemu_socket_try_set_nonblock(sioc->fd);