diff --git a/mercurial/ui.py b/mercurial/ui.py
index 05203eae5e..d2bc05ba89 100644
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -15,7 +15,7 @@ _booleans = {'1':True, 'yes':True, 'true':True, 'on':True,
 class ui(object):
     def __init__(self, src=None):
         self._buffers = []
-        self.quiet = self.verbose = self.debugflag = self.traceback = False
+        self.quiet = self.verbose = self.debugflag = self._traceback = False
         self.interactive = self._reportuntrusted = True
         self._ocfg = config.config() # overlay
         self._tcfg = config.config() # trusted
@@ -113,7 +113,7 @@ class ui(object):
             self.quiet = self.verbose = False
         self._reportuntrusted = self.configbool("ui", "report_untrusted", True)
         self.interactive = self.configbool("ui", "interactive", self.isatty())
-        self.traceback = self.configbool('ui', 'traceback', False)
+        self._traceback = self.configbool('ui', 'traceback', False)
 
         # update trust information
         for user in self.configlist('trusted', 'users'):
@@ -338,9 +338,9 @@ class ui(object):
         '''print exception traceback if traceback printing enabled.
         only to call in exception handler. returns true if traceback
         printed.'''
-        if self.traceback:
+        if self._traceback:
             traceback.print_exc()
-        return self.traceback
+        return self._traceback
 
     def geteditor(self):
         '''return editor to use'''