diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -4552,7 +4552,7 @@ def showconfig(ui, repo, *values, **opts
     """
 
     for f in scmutil.rcpath():
-        ui.debug(_('read config from: %s\n') % f)
+        ui.debug('read config from: %s\n' % f)
     untrusted = bool(opts.get('untrusted'))
     if values:
         sections = [v for v in values if '.' not in v]
diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -267,8 +267,8 @@ class cmdalias(object):
                     elif int(m.groups()[0]) <= len(args):
                         return m.group()
                     else:
-                        ui.debug(_("No argument found for substitution "
-                                   "of %i variable in alias '%s' definition.")
+                        ui.debug("No argument found for substitution "
+                                 "of %i variable in alias '%s' definition."
                                  % (int(m.groups()[0]), self.name))
                         return ''
                 cmd = re.sub(r'\$(\d+|\$)', _checkvar, self.definition[1:])
diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -159,8 +159,8 @@ class ui(object):
         if self.debugflag and not untrusted and self._reportuntrusted:
             uvalue = self._ucfg.get(section, name)
             if uvalue is not None and uvalue != value:
-                self.debug(_("ignoring untrusted configuration option "
-                             "%s.%s = %s\n") % (section, name, uvalue))
+                self.debug("ignoring untrusted configuration option "
+                           "%s.%s = %s\n" % (section, name, uvalue))
         return value
 
     def configpath(self, section, name, default=None, untrusted=False):
@@ -330,8 +330,8 @@ class ui(object):
         if self.debugflag and not untrusted and self._reportuntrusted:
             for k, v in self._ucfg.items(section):
                 if self._tcfg.get(section, k) != v:
-                    self.debug(_("ignoring untrusted configuration option "
-                                "%s.%s = %s\n") % (section, k, v))
+                    self.debug("ignoring untrusted configuration option "
+                               "%s.%s = %s\n" % (section, k, v))
         return items
 
     def walkconfig(self, untrusted=False):