diff --git a/mercurial/byterange.py b/mercurial/byterange.py
--- a/mercurial/byterange.py
+++ b/mercurial/byterange.py
@@ -416,7 +416,7 @@
     if range_header is None:
         return None
     if _rangere is None:
-        _rangere = re.compile(r'^bytes=(\d{1,})-(\d*)')
+        _rangere = re.compile(br'^bytes=(\d{1,})-(\d*)')
     match = _rangere.match(range_header)
     if match:
         tup = range_tuple_normalize(match.group(1, 2))
diff --git a/mercurial/mdiff.py b/mercurial/mdiff.py
--- a/mercurial/mdiff.py
+++ b/mercurial/mdiff.py
@@ -100,7 +100,7 @@
     if blank and opts.ignoreblanklines:
         text = re.sub('\n+', '\n', text).strip('\n')
     if opts.ignorewseol:
-        text = re.sub(r'[ \t\r\f]+\n', r'\n', text)
+        text = re.sub(br'[ \t\r\f]+\n', r'\n', text)
     return text
 
 def splitblock(base1, lines1, base2, lines2, opts):