diff --git a/WebHostLib/customserver.py b/WebHostLib/customserver.py
index f9f45eebd3..a378959e74 100644
--- a/WebHostLib/customserver.py
+++ b/WebHostLib/customserver.py
@@ -270,7 +270,7 @@ def get_active_net_connections() -> typing.Iterable[int]:
 
 def get_used_ports():
     last_used_ports: tuple[frozenset[int], float] = getattr(get_used_ports, "last", None)
-    t_hash = time.time() // 900
+    t_hash = round(time.time() / 90)  # cache for 90 seconds
     if last_used_ports is None or last_used_ports[1] != t_hash:
         last_used_ports = (frozenset(get_active_net_connections()), t_hash)
         setattr(get_used_ports, "last", last_used_ports)