diff --git a/mercurial/sshpeer.py b/mercurial/sshpeer.py
--- a/mercurial/sshpeer.py
+++ b/mercurial/sshpeer.py
@@ -130,7 +130,7 @@ class doublepipe:
             if sideready:
                 _forwardoutput(self._ui, self._side)
             if mainready:
-                meth = getattr(self._main, methname)
+                meth = getattr(self._main, pycompat.sysstr(methname))
                 if data is None:
                     return meth()
                 else: