Indent string when replying messages

[f.sa...@gmail.com]

Hello. I've been playing with mutt for a few days and have configured
most of the stuff at will. However, there's one little detail that I
still haven't got hold of. When replying a message, the original
message is quoted with a ">" at the beginning of the line.

The problem is that no space is shown after the ">". I've tried

set indent_string = "> "

(extra space after the sign) but it won't work either.

Anybody knows the way to make a space appear after the ">"?

Thank you very much.

Cesc