diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -140,6 +140,9 @@ coreconfigitem('server', 'uncompressedal
 coreconfigitem('server', 'validate',
     default=False,
 )
+coreconfigitem('server', 'zliblevel',
+    default=-1,
+)
 coreconfigitem('ui', 'clonebundleprefers',
     default=list,
 )
diff --git a/mercurial/hgweb/protocol.py b/mercurial/hgweb/protocol.py
--- a/mercurial/hgweb/protocol.py
+++ b/mercurial/hgweb/protocol.py
@@ -135,7 +135,7 @@ class webproto(wireproto.abstractserverp
         # Don't allow untrusted settings because disabling compression or
         # setting a very high compression level could lead to flooding
         # the server's network or CPU.
-        opts = {'level': self.ui.configint('server', 'zliblevel', -1)}
+        opts = {'level': self.ui.configint('server', 'zliblevel')}
         return HGTYPE, util.compengines['zlib'], opts
 
 def iscmd(cmd):