diff --git a/mercurial/wireprotoserver.py b/mercurial/wireprotoserver.py
--- a/mercurial/wireprotoserver.py
+++ b/mercurial/wireprotoserver.py
@@ -445,7 +445,7 @@
                 _sshv1respondstream(self._fout, rsp)
             elif isinstance(rsp, wireprototypes.pushres):
                 _sshv1respondbytes(self._fout, b'')
-                _sshv1respondbytes(self._fout, bytes(rsp.res))
+                _sshv1respondbytes(self._fout, b'%d' % rsp.res)
             elif isinstance(rsp, wireprototypes.pusherr):
                 _sshv1respondbytes(self._fout, rsp.res)
             elif isinstance(rsp, wireprototypes.ooberror):