diff --git a/spnego.go b/spnego.go
index 4f9c61f..70c331b 100644
--- a/spnego.go
+++ b/spnego.go
@@ -40,6 +40,11 @@ func getHostname(req *http.Request, canonicalize bool) (string, error) {
 	if req.Host != "" {
 		h = req.Host
 	}
+	// I can't think why you'd want to canonicalize an overridden Host
+	// header (you're likely to get the hostname in the URL, which is what
+	// you're overriding in the first place). But since it can be disabled,
+	// leave it here in the flow so that Host header hostnames can be
+	// canonicalized if desired.
 	if canonicalize {
 		if h, err = canonicalizeHostname(h); err != nil {
 			return "", err