diff --git a/Lib/wsgiref/headers.py b/Lib/wsgiref/headers.py
index 3169acf..02fd6a0 100644
--- a/Lib/wsgiref/headers.py
+++ b/Lib/wsgiref/headers.py
@@ -8,7 +8,7 @@
 from types import ListType, TupleType
 
 # Regular expression that matches `special' characters in parameters, the
-# existance of which force quoting of the parameter value.
+# existence of which force quoting of the parameter value.
 import re
 tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]')