diff --git a/WebHostLib/customserver.py b/WebHostLib/customserver.py
index 44271d7069..3f31d92116 100644
--- a/WebHostLib/customserver.py
+++ b/WebHostLib/customserver.py
@@ -261,14 +261,13 @@ def get_active_net_connections() -> typing.Iterable[int]:
         ))
 
 
-_last_used_ports = (frozenset(get_active_net_connections()), round(time.time() / 900))
 def get_used_ports():
-    global _last_used_ports
-    t_hash = round(time.time() / 900)
-    if _last_used_ports[1] != t_hash:
-        _last_used_ports = (frozenset(get_active_net_connections()), t_hash)
+    last_used_ports: tuple[frozenset[int], int] = getattr(get_used_ports, "last", None)
+    t_hash = time.time() // 900
+    if last_used_ports is None or last_used_ports[1] != t_hash:
+        setattr(get_used_ports, "last", (frozenset(get_active_net_connections()), t_hash))
 
-    return _last_used_ports[0]
+    return last_used_ports[0]
 
 
 def create_socket_from_port_list(available_ports: typing.Iterable[int], host: str) -> socket.socket | None: