diff --git a/components/net/hsts.rs b/components/net/hsts.rs
index 2945ce0dbe5..db9dcb4b9d3 100644
--- a/components/net/hsts.rs
+++ b/components/net/hsts.rs
@@ -125,7 +125,11 @@ pub fn secure_url(url: &Url) -> Url {
     if &*url.scheme == "http" {
         let mut secure_url = url.clone();
         secure_url.scheme = "https".to_string();
-        Url::parse(&secure_url.serialize()).unwrap()
+        secure_url.relative_scheme_data_mut()
+            .map(|scheme_data| {
+                scheme_data.default_port = Some(443);
+            });
+        secure_url
     } else {
         url.clone()
     }