diff --git a/mercurial/pure/base85.py b/mercurial/pure/base85.py
--- a/mercurial/pure/base85.py
+++ b/mercurial/pure/base85.py
@@ -9,8 +9,10 @@
 
 import struct
 
-_b85chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
-            "abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"
+from .. import pycompat
+
+_b85chars = pycompat.bytestr("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef"
+                             "ghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~")
 _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
 _b85dec = {}