diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -736,6 +736,9 @@ coreconfigitem('web', 'contact',
 coreconfigitem('web', 'deny_push',
     default=list,
 )
+coreconfigitem('web', 'guessmime',
+    default=False,
+)
 coreconfigitem('web', 'accesslog',
     default='-',
 )
diff --git a/mercurial/hgweb/webcommands.py b/mercurial/hgweb/webcommands.py
--- a/mercurial/hgweb/webcommands.py
+++ b/mercurial/hgweb/webcommands.py
@@ -93,7 +93,7 @@ def log(web, req, tmpl):
 
 @webcommand('rawfile')
 def rawfile(web, req, tmpl):
-    guessmime = web.configbool('web', 'guessmime', False)
+    guessmime = web.configbool('web', 'guessmime')
 
     path = webutil.cleanpath(web.repo, req.form.get('file', [''])[0])
     if not path: