diff --git a/src/waitress/trigger.py b/src/waitress/trigger.py
index 24c4d0d6..4fc26434 100644
--- a/src/waitress/trigger.py
+++ b/src/waitress/trigger.py
@@ -174,7 +174,7 @@ def __init__(self, map):
                     w.connect(connect_address)
                     break  # success
                 except OSError as detail:
-                    if detail[0] != errno.WSAEADDRINUSE:
+                    if getattr('winerror', detail, None) != errno.WSAEADDRINUSE:
                         # "Address already in use" is the only error
                         # I've seen on two WinXP Pro SP2 boxes, under
                         # Pythons 2.3.5 and 2.4.1.