diff --git a/api/image.go b/api/image.go
index 58a09a6..a0d84a9 100644
--- a/api/image.go
+++ b/api/image.go
@@ -47,7 +47,7 @@ func Image(w http.ResponseWriter, r *http.Request) {
 		} else {
 			u.Scheme = r.URL.Scheme
 		}
-		u.Host = r.URL.Host
+		u.Host = r.Host
 	}
 
 	if _, some := params["threshold"]; !some {