diff --git a/gateway/platforms/shared_ingress.py b/gateway/platforms/shared_ingress.py
index ae3db657e6..8018ce1290 100644
--- a/gateway/platforms/shared_ingress.py
+++ b/gateway/platforms/shared_ingress.py
@@ -24,6 +24,11 @@ logger = logging.getLogger(__name__)
 _WILDCARD_HOSTS = frozenset({"", "0.0.0.0", "::", "*"})
 
 
+def is_wildcard_host(host: Any) -> bool:
+    """True for the dual-stack default (None/"") and the per-family wildcards."""
+    return host is None or str(host).strip() in _WILDCARD_HOSTS
+
+
 def shared_ingress_profile(adapter: Any) -> Optional[str]:
     """Profile name when *adapter* was constructed in shared-listener mode, else None."""
     return getattr(adapter, "_shared_listener_profile", None) or None
@@ -31,7 +36,7 @@ def shared_ingress_profile(adapter: Any) -> Optional[str]:
 
 def listener_base_url(host: Any, port: Any) -> str:
     """``http://host:port`` clients use to reach a listener bound on ``host`` (wildcards → loopback)."""
-    host = "127.0.0.1" if host is None or str(host).strip() in _WILDCARD_HOSTS else str(host)
+    host = "127.0.0.1" if is_wildcard_host(host) else str(host)
     if ":" in host and not host.startswith("["):
         host = f"[{host}]"
     return f"http://{host}:{port or 0}"
diff --git a/gateway/platforms/tcp_site.py b/gateway/platforms/tcp_site.py
index 6160075a5a..6be1aa63b2 100644
--- a/gateway/platforms/tcp_site.py
+++ b/gateway/platforms/tcp_site.py
@@ -10,16 +10,10 @@ from typing import Optional
 
 from aiohttp import web
 
+from gateway.platforms.shared_ingress import is_wildcard_host
+
 logger = logging.getLogger(__name__)
 
-_WILDCARD_HOSTS = frozenset({"0.0.0.0", "::"})
-
-
-def is_wildcard_host(host: Optional[str]) -> bool:
-    """True for the dual-stack default (None/"") and the per-family wildcards."""
-    return not host or host.strip() in _WILDCARD_HOSTS
-
-
 def has_live_listener(host: str, port: int) -> bool:
     """Blocking probe: True when something accepts connections on ``host:port``. Refused = nobody listens;
     any other failure (timeout, unroutable) is treated as live so the caller stays exclusive."""