diff --git a/mercurial/pvec.py b/mercurial/pvec.py
--- a/mercurial/pvec.py
+++ b/mercurial/pvec.py
@@ -76,7 +76,7 @@
 def _str(v, l):
     bs = b""
     for p in pycompat.xrange(l):
-        bs = chr(v & 255) + bs
+        bs = pycompat.bytechr(v & 255) + bs
         v >>= 8
     return bs