diff --git a/python/sglang/srt/server_args.py b/python/sglang/srt/server_args.py
index ef4df60a5..09d1a3ede 100644
--- a/python/sglang/srt/server_args.py
+++ b/python/sglang/srt/server_args.py
@@ -928,7 +928,10 @@ class PortArgs:
         while True:
             if is_port_available(port):
                 break
-            port += 42
+            if port < 60000:
+                port += 42
+            else:
+                port -= 43
 
         return PortArgs(
             tokenizer_ipc_name=tempfile.NamedTemporaryFile(delete=False).name,
diff --git a/python/sglang/srt/utils.py b/python/sglang/srt/utils.py
index 44a5e41a4..b07f6f01d 100644
--- a/python/sglang/srt/utils.py
+++ b/python/sglang/srt/utils.py
@@ -335,6 +335,8 @@ def is_port_available(port):
             return True
         except socket.error:
             return False
+        except OverflowError:
+            return False
 
 
 def decode_video_base64(video_base64):