diff --git a/Lib/urllib.py b/Lib/urllib.py
index 1553f9d..84e9dbc 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1396,7 +1396,7 @@
 
                 else:
                     mask = int(mask[1:])
-                    mask = 32 - mask
+                mask = 32 - mask
 
                 if (hostIP >> mask) == (base >> mask):
                     return True
diff --git a/Misc/NEWS b/Misc/NEWS
index 16ab295..af1ba7f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -43,6 +43,9 @@
 Library
 -------
 
+- Issue #11500: Fixed a bug in the os x proxy bypass code for fully qualified 
+  IP addresses in the proxy exception list. 
+
 - Issue #11131: Fix sign of zero in plus and minus operations when
   the context rounding mode is ROUND_FLOOR.