diff --git a/http.go b/http.go
index a0b39f5..e97fb35 100644
--- a/http.go
+++ b/http.go
@@ -54,7 +54,7 @@ func (s *Service) Webfinger(w http.ResponseWriter, r *http.Request) {
 		rels = append(rels, Rel(r))
 	}
 
-	rsc, err := s.Resolver.FindUser(a.Name, a.Hostname, rels)
+	rsc, err := s.Resolver.FindUser(a.Name, a.Hostname, r.Host, rels)
 	if err != nil {
 		if !s.Resolver.IsNotFoundError(err) {
 			s.ErrorHandler.ServeHTTP(w, addError(r, err))
diff --git a/http_test.go b/http_test.go
index a8cb08f..268d48d 100644
--- a/http_test.go
+++ b/http_test.go
@@ -19,7 +19,7 @@ import (
 type dummyUserResolver struct {
 }
 
-func (d *dummyUserResolver) FindUser(username string, hostname string, rel []Rel) (*Resource, error) {
+func (d *dummyUserResolver) FindUser(username string, hostname, requestHost string, rel []Rel) (*Resource, error) {
 	if username == "hello" {
 		if len(rel) == 2 && rel[0] == "x" && rel[1] == "y" {
 			return &Resource{
diff --git a/resolver.go b/resolver.go
index abc86b3..989a9e8 100644
--- a/resolver.go
+++ b/resolver.go
@@ -6,7 +6,7 @@ package webfinger
 type Resolver interface {
 
 	// FindUser finds the user given the username and hostname.
-	FindUser(username string, hostname string, r []Rel) (*Resource, error)
+	FindUser(username string, hostname, requestHost string, r []Rel) (*Resource, error)
 
 	// DummyUser allows us to return a dummy user to avoid user-enumeration via webfinger 404s. This
 	// can be done in the webfinger code itself but then it would be obvious which users are real