diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index 1dda966..773025a 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -2265,7 +2265,8 @@
     # strip port off host
     hostonly, port = splitport(host)
     # check if the host ends with any of the DNS suffixes
-    for name in no_proxy.split(','):
+    no_proxy_list = [proxy.strip() for proxy in no_proxy.split(',')]
+    for name in no_proxy_list:
         if name and (hostonly.endswith(name) or host.endswith(name)):
             return 1
     # otherwise, don't bypass