diff --git a/Lib/difflib.py b/Lib/difflib.py
index 1c6fbdb..788a92d 100644
--- a/Lib/difflib.py
+++ b/Lib/difflib.py
@@ -1103,7 +1103,7 @@
 
 import re
 
-def IS_LINE_JUNK(line, pat=re.compile(r"\s*#?\s*$").match):
+def IS_LINE_JUNK(line, pat=re.compile(r"\s*(?:#\s*)?$").match):
     r"""
     Return 1 for ignorable line: iff `line` is blank or contains a single '#'.