diff --git a/lib/rack/urlmap.rb b/lib/rack/urlmap.rb
index afb97eea4..99c4d8236 100644
--- a/lib/rack/urlmap.rb
+++ b/lib/rack/urlmap.rb
@@ -37,7 +37,7 @@ def remap(map)
         end
 
         location = location.chomp('/')
-        match = Regexp.new("^#{Regexp.quote(location).gsub('/', '/+')}(.*)", nil, 'n')
+        match = Regexp.new("^#{Regexp.quote(location).gsub('/', '/+')}(.*)", Regexp::NOENCODING)
 
         [host, location, match, app]
       }.sort_by do |(host, location, _, _)|