diff --git a/components/script/stylesheet_loader.rs b/components/script/stylesheet_loader.rs
index 9185bb7f134..cdafde510c9 100644
--- a/components/script/stylesheet_loader.rs
+++ b/components/script/stylesheet_loader.rs
@@ -161,6 +161,7 @@ impl FetchResponseListener for StylesheetContext {
                                                   &data,
                                                   protocol_encoding_label,
                                                   Some(environment_encoding),
+                                                  &final_url,
                                                   Some(&loader),
                                                   win.css_error_reporter());
                 }
diff --git a/components/style/encoding_support.rs b/components/style/encoding_support.rs
index 6712af0387e..ce7aa43c1fd 100644
--- a/components/style/encoding_support.rs
+++ b/components/style/encoding_support.rs
@@ -74,12 +74,14 @@ impl Stylesheet {
                              bytes: &[u8],
                              protocol_encoding_label: Option<&str>,
                              environment_encoding: Option<EncodingRef>,
+                             url_data: &UrlExtraData,
                              stylesheet_loader: Option<&StylesheetLoader>,
                              error_reporter: &ParseErrorReporter) {
         let (string, _) = decode_stylesheet_bytes(
             bytes, protocol_encoding_label, environment_encoding);
         Self::update_from_str(existing,
                               &string,
+                              url_data,
                               stylesheet_loader,
                               error_reporter)
     }
diff --git a/components/style/stylesheets.rs b/components/style/stylesheets.rs
index c0ac68cf922..f59aceb9e61 100644
--- a/components/style/stylesheets.rs
+++ b/components/style/stylesheets.rs
@@ -595,11 +595,14 @@ impl Stylesheet {
     /// Updates an empty stylesheet from a given string of text.
     pub fn update_from_str(existing: &Stylesheet,
                            css: &str,
+                           url_data: &UrlExtraData,
                            stylesheet_loader: Option<&StylesheetLoader>,
                            error_reporter: &ParseErrorReporter) {
         let mut namespaces = Namespaces::default();
+        // FIXME: we really should update existing.url_data with the given url_data,
+        // otherwise newly inserted rule may not have the right base url.
         let (rules, dirty_on_viewport_size_change) = Stylesheet::parse_rules(
-            css, &existing.url_data, existing.origin, &mut namespaces,
+            css, url_data, existing.origin, &mut namespaces,
             &existing.shared_lock, stylesheet_loader, error_reporter,
         );
 
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 14a313b4187..ffebdb38b56 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -364,9 +364,10 @@ pub extern "C" fn Servo_StyleSheet_ClearAndUpdate(stylesheet: RawServoStyleSheet
                                                   loader: *mut Loader,
                                                   gecko_stylesheet: *mut ServoStyleSheet,
                                                   data: *const nsACString,
-                                                  _extra_data: *mut URLExtraData)
+                                                  extra_data: *mut URLExtraData)
 {
     let input = unsafe { data.as_ref().unwrap().as_str_unchecked() };
+    let url_data = unsafe { RefPtr::from_ptr_ref(&extra_data) };
 
     let loader = if loader.is_null() {
         None
@@ -381,7 +382,8 @@ pub extern "C" fn Servo_StyleSheet_ClearAndUpdate(stylesheet: RawServoStyleSheet
     };
 
     let sheet = Stylesheet::as_arc(&stylesheet);
-    Stylesheet::update_from_str(&sheet, input, loader, &StdoutErrorReporter);
+    Stylesheet::update_from_str(&sheet, input, url_data,
+                                loader, &StdoutErrorReporter);
 }
 
 #[no_mangle]