diff --git a/port_prediction.nim b/port_prediction.nim
index 905f79d..5fca2bd 100644
--- a/port_prediction.nim
+++ b/port_prediction.nim
@@ -84,12 +84,12 @@ proc predictPortRange*(localPort: Port, probedPorts: seq[Port]): seq[Port] =
         return
   # assume symmetric NAT with random port mapping
   randomize()
-  let first = if minPort >= 1024 + 5000:
-    minPort - 5000
+  let first = if minPort >= 1024 + 10000:
+    minPort - 10000
   else:
     1024
-  let last = if maxPort <= uint16.high - 5000:
-    maxPort + 5000
+  let last = if maxPort <= uint16.high - 10000:
+    maxPort + 10000
   else:
     uint16.high
   for _ in 1 .. RandomPortCount: