diff --git a/lib/webrick/httpservlet/filehandler.rb b/lib/webrick/httpservlet/filehandler.rb
index 0780faf202..2044d6eabe 100644
--- a/lib/webrick/httpservlet/filehandler.rb
+++ b/lib/webrick/httpservlet/filehandler.rb
@@ -42,6 +42,11 @@ module WEBrick
       # :stopdoc:
 
       def do_GET(req, res)
+        case enc = Encoding.find('filesystem')
+        when Encoding::US_ASCII, Encoding::ASCII_8BIT
+        else
+          @local_path = @local_path.dup.force_encoding(enc)
+        end
         st = File::stat(@local_path)
         mtime = st.mtime
         res['etag'] = sprintf("%x-%x-%x", st.ino, st.size, st.mtime.to_i)