diff --git a/copyparty/__main__.py b/copyparty/__main__.py
index 05e11463..90b4c626 100755
--- a/copyparty/__main__.py
+++ b/copyparty/__main__.py
@@ -672,6 +672,8 @@ def add_network(ap):
     ap2.add_argument("--rp-loc", metavar="PATH", type=u, default="", help="if reverse-proxying on a location instead of a dedicated domain/subdomain, provide the base location here (eg. /foo/bar)")
     if ANYWIN:
         ap2.add_argument("--reuseaddr", action="store_true", help="set reuseaddr on listening sockets on windows; allows rapid restart of copyparty at the expense of being able to accidentally start multiple instances")
+    else:
+        ap2.add_argument("--freebind", action="store_true", help="allow listening on IPs which do not yet exist, for example if the network interfaces haven't finished going up. Only makes sense for IPs other than '0.0.0.0', '127.0.0.1', '::', and '::1'. May require running as root (unless net.ipv6.ip_nonlocal_bind)")
     ap2.add_argument("--s-wr-sz", metavar="B", type=int, default=256*1024, help="socket write size in bytes")
     ap2.add_argument("--s-wr-slp", metavar="SEC", type=float, default=0, help="debug: socket write delay in seconds")
     ap2.add_argument("--rsp-slp", metavar="SEC", type=float, default=0, help="debug: response delay in seconds")
diff --git a/copyparty/multicast.py b/copyparty/multicast.py
index a04e5d73..9baed3df 100644
--- a/copyparty/multicast.py
+++ b/copyparty/multicast.py
@@ -15,7 +15,7 @@ from ipaddress import (
 )
 
 from .__init__ import TYPE_CHECKING
-from .util import MACOS, Netdev, min_ex, spack
+from .util import MACOS, Netdev, find_prefix, min_ex, spack
 
 if TYPE_CHECKING:
     from .svchub import SvcHub
@@ -110,9 +110,7 @@ class MCast(object):
             )
 
         ips = [x for x in ips if x not in ("::1", "127.0.0.1")]
-
-        # ip -> ip/prefix
-        ips = [[x for x in netdevs if x.startswith(y + "/")][0] for y in ips]
+        ips = find_prefix(ips, netdevs)
 
         on = self.on[:]
         off = self.off[:]
diff --git a/copyparty/tcpsrv.py b/copyparty/tcpsrv.py
index 5ad25ed7..826e56c7 100644
--- a/copyparty/tcpsrv.py
+++ b/copyparty/tcpsrv.py
@@ -29,6 +29,9 @@ if TYPE_CHECKING:
 if not hasattr(socket, "IPPROTO_IPV6"):
     setattr(socket, "IPPROTO_IPV6", 41)
 
+if not hasattr(socket, "IP_FREEBIND"):
+    setattr(socket, "IP_FREEBIND", 15)
+
 
 class TcpSrv(object):
     """
@@ -224,6 +227,9 @@ class TcpSrv(object):
         except:
             pass  # will create another ipv4 socket instead
 
+        if not ANYWIN and self.args.freebind:
+            srv.setsockopt(socket.SOL_IP, socket.IP_FREEBIND, 1)
+
         try:
             srv.bind((ip, port))
             self.srv.append(srv)
diff --git a/copyparty/util.py b/copyparty/util.py
index c816d9be..ad65992b 100644
--- a/copyparty/util.py
+++ b/copyparty/util.py
@@ -471,7 +471,7 @@ class NetMap(object):
             )
 
         ips = [x for x in ips if x not in ("::1", "127.0.0.1")]
-        ips = [[x for x in netdevs if x.startswith(y + "/")][0] for y in ips]
+        ips = find_prefix(ips, netdevs)
 
         self.cache: dict[str, str] = {}
         self.b2sip: dict[bytes, str] = {}
@@ -1714,6 +1714,15 @@ def ipnorm(ip: str) -> str:
     return ip
 
 
+def find_prefix(ips: list[str], netdevs: dict[str, Netdev]) -> list[str]:
+    ret = []
+    for ip in ips:
+        hit = next((x for x in netdevs if x.startswith(ip + "/")), None)
+        if hit:
+            ret.append(hit)
+    return ret
+
+
 def html_escape(s: str, quot: bool = False, crlf: bool = False) -> str:
     """html.escape but also newlines"""
     s = s.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")