diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -122,8 +122,8 @@ class ui(object):
             self.quiet = not self.debugflag and self.configbool('ui', 'quiet')
             if self.verbose and self.quiet:
                 self.quiet = self.verbose = False
-            self._reportuntrusted = self.configbool("ui", "report_untrusted",
-                                        True)
+            self._reportuntrusted = self.debugflag or self.configbool("ui",
+                "report_untrusted", True)
             self.tracebackflag = self.configbool('ui', 'traceback', False)
 
         if section in (None, 'trusted'):
diff --git a/tests/test-trusted.py b/tests/test-trusted.py
--- a/tests/test-trusted.py
+++ b/tests/test-trusted.py
@@ -11,7 +11,8 @@ basehgrc = f.read()
 f.close()
 
 def testui(user='foo', group='bar', tusers=(), tgroups=(),
-           cuser='foo', cgroup='bar', debug=False, silent=False):
+           cuser='foo', cgroup='bar', debug=False, silent=False,
+           report=True):
     # user, group => owners of the file
     # tusers, tgroups => trusted users/groups
     # cuser, cgroup => user/group of the current process
@@ -61,6 +62,7 @@ def testui(user='foo', group='bar', tuse
 
     u = ui.ui()
     u.setconfig('ui', 'debug', str(bool(debug)))
+    u.setconfig('ui', 'report_untrusted', str(bool(report)))
     u.readconfig('.hg/hgrc')
     if silent:
         return u
@@ -131,6 +133,12 @@ testui(user='abc', group='def', cuser=No
 print "# prints debug warnings"
 u = testui(user='abc', group='def', cuser='foo', debug=True)
 
+print "# report_untrusted enabled without debug hides warnings"
+u = testui(user='abc', group='def', cuser='foo', report=False)
+
+print "# report_untrusted enabled with debug shows warnings"
+u = testui(user='abc', group='def', cuser='foo', debug=True, report=False)
+
 print "# ui.readconfig sections"
 filename = 'foobar'
 f = open(filename, 'w')
diff --git a/tests/test-trusted.py.out b/tests/test-trusted.py.out
--- a/tests/test-trusted.py.out
+++ b/tests/test-trusted.py.out
@@ -136,6 +136,25 @@ untrusted
 .ignoring untrusted configuration option paths.local = /another/path
 . local = /another/path
 
+# report_untrusted enabled without debug hides warnings
+# different user, different group
+trusted
+    global = /some/path
+untrusted
+. . global = /some/path
+. . local = /another/path
+
+# report_untrusted enabled with debug shows warnings
+# different user, different group
+Not trusting file .hg/hgrc from untrusted user abc, group def
+trusted
+ignoring untrusted configuration option paths.local = /another/path
+    global = /some/path
+untrusted
+. . global = /some/path
+.ignoring untrusted configuration option paths.local = /another/path
+. local = /another/path
+
 # ui.readconfig sections
 quux