Resolving install directory 404

My WordPress Address (URL) http://mydomain.com/wordpress My Site Address (URL) is http://mydomian.com My site works fine when accessed from http://mydomian.com and I have no problems to speak of, but: http://mydomain.com/wordpress gives me a 404.

This is a problem (in fact I only noticed it) because IFTTT.com will only activate a WordPress channel when I use http://mydomain.com/wordpress as my WordPress URL. And then it does activate just fine. But all my recipes fail because this same URL 404s.

What is the best/preferred way to redirect http://mydomain.com/wordpress to http://mydomain.com for the sake of IFTTT without breaking the everything-else-is-fine-ness of the site?