diff --git a/mercurial/hgweb/hgweb_mod.py b/mercurial/hgweb/hgweb_mod.py
--- a/mercurial/hgweb/hgweb_mod.py
+++ b/mercurial/hgweb/hgweb_mod.py
@@ -378,7 +378,7 @@
                     req.env.get('X-HgHttp2', '')):
                     req.drain()
                 else:
-                    req.headers.append(('Connection', 'Close'))
+                    req.headers.append((r'Connection', r'Close'))
                 req.respond(inst, protocol.HGTYPE,
                             body='0\n%s\n' % inst)
                 return ''
diff --git a/mercurial/hgweb/protocol.py b/mercurial/hgweb/protocol.py
--- a/mercurial/hgweb/protocol.py
+++ b/mercurial/hgweb/protocol.py
@@ -75,10 +75,10 @@
         args.update(cgi.parse_qs(argvalue, keep_blank_values=True))
         return args
     def getfile(self, fp):
-        length = int(self.req.env['CONTENT_LENGTH'])
+        length = int(self.req.env[r'CONTENT_LENGTH'])
         # If httppostargs is used, we need to read Content-Length
         # minus the amount that was consumed by args.
-        length -= int(self.req.env.get('HTTP_X_HGARGS_POST', 0))
+        length -= int(self.req.env.get(r'HTTP_X_HGARGS_POST', 0))
         for s in util.filechunkiter(self.req, limit=length):
             fp.write(s)
     def redirect(self):
diff --git a/mercurial/hgweb/server.py b/mercurial/hgweb/server.py
--- a/mercurial/hgweb/server.py
+++ b/mercurial/hgweb/server.py
@@ -194,9 +194,9 @@
             self._chunked = (not self.close_connection and
                              self.request_version == "HTTP/1.1")
             if self._chunked:
-                self.send_header('Transfer-Encoding', 'chunked')
+                self.send_header(r'Transfer-Encoding', r'chunked')
             else:
-                self.send_header('Connection', 'close')
+                self.send_header(r'Connection', r'close')
         self.end_headers()
         self.sent_headers = True