diff --git a/components/net/image_cache_thread.rs b/components/net/image_cache_thread.rs
index 7ef657e345f..2df54b8e30c 100644
--- a/components/net/image_cache_thread.rs
+++ b/components/net/image_cache_thread.rs
@@ -5,7 +5,7 @@
 use immeta::load_from_buf;
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use ipc_channel::router::ROUTER;
-use net_traits::{CoreResourceThread, NetworkError, fetch_async, FetchResponseMsg, FetchMetadata, Metadata};
+use net_traits::{CoreResourceThread, NetworkError, fetch_async, FetchResponseMsg};
 use net_traits::image::base::{Image, ImageMetadata, PixelFormat, load_from_memory};
 use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheCommand, ImageCacheThread, ImageState};
 use net_traits::image_cache_thread::{ImageCacheResult, ImageOrMetadataAvailable, ImageResponse, UsePlaceholder};
diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index 6329a81048f..d68b1adf33e 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -4260,7 +4260,9 @@ class CGUnionConversionStruct(CGThing):
 
         return CGWrapper(
             CGIndenter(jsConversion, 4),
-            pre="unsafe fn TryConvertTo%s(cx: *mut JSContext, value: HandleValue) -> %s {\n" % (t.name, returnType),
+            # TryConvertToObject is unused, but not generating it while generating others is tricky.
+            pre="#[allow(dead_code)] unsafe fn TryConvertTo%s(cx: *mut JSContext, value: HandleValue) -> %s {\n"
+                % (t.name, returnType),
             post="\n}")
 
     def define(self):
diff --git a/components/script/dom/htmlmediaelement.rs b/components/script/dom/htmlmediaelement.rs
index 8a3f35c23d4..ad899de4c9d 100644
--- a/components/script/dom/htmlmediaelement.rs
+++ b/components/script/dom/htmlmediaelement.rs
@@ -437,6 +437,7 @@ impl HTMLMediaElement {
     }
 
     // https://html.spec.whatwg.org/multipage/#concept-media-load-algorithm
+    #[allow(unreachable_code)]
     fn resource_selection_algorithm_sync(&self, base_url: ServoUrl) {
         // TODO step 5 (populate pending text tracks)
 
@@ -446,7 +447,7 @@ impl HTMLMediaElement {
             ResourceSelectionMode::Object
         } else if let Some(attr) = self.upcast::<Element>().get_attribute(&ns!(), &local_name!("src")) {
             ResourceSelectionMode::Attribute(attr.Value().to_string())
-        } else if false {
+        } else if false {  // TODO: when implementing this remove #[allow(unreachable_code)] above.
             // TODO <source> child
             ResourceSelectionMode::Children(panic!())
         } else {
diff --git a/components/style/viewport.rs b/components/style/viewport.rs
index bbdd3a2ed35..2e965da4e54 100644
--- a/components/style/viewport.rs
+++ b/components/style/viewport.rs
@@ -69,7 +69,7 @@ macro_rules! declare_viewport_descriptor_inner {
         const VIEWPORT_DESCRIPTOR_VARIANTS: usize = $number_of_variants;
 
         impl ViewportDescriptor {
-            fn discriminant_value(&self) -> usize {
+            pub fn discriminant_value(&self) -> usize {
                 match *self {
                     $(
                         ViewportDescriptor::$assigned_variant(..) => $assigned_discriminant,
diff --git a/ports/cef/lib.rs b/ports/cef/lib.rs
index e270267b905..3e44e308091 100644
--- a/ports/cef/lib.rs
+++ b/ports/cef/lib.rs
@@ -6,7 +6,6 @@
 #![feature(core_intrinsics)]
 #![feature(link_args)]
 #![feature(plugin)]
-#![feature(unicode)]
 
 #![allow(non_camel_case_types)]
 
@@ -22,7 +21,6 @@ extern crate euclid;
 extern crate gfx_traits;
 extern crate gleam;
 extern crate glutin_app;
-extern crate rustc_unicode;
 extern crate script_traits;
 extern crate servo_config;
 extern crate servo_geometry;
diff --git a/ports/cef/string_list.rs b/ports/cef/string_list.rs
index 90ada69267a..fc6de158bd9 100644
--- a/ports/cef/string_list.rs
+++ b/ports/cef/string_list.rs
@@ -7,8 +7,6 @@ use std::slice;
 use string::cef_string_utf16_set;
 use types::{cef_string_list_t,cef_string_t};
 
-use rustc_unicode::str::Utf16Encoder;
-
 //cef_string_list
 
 #[no_mangle]
@@ -38,7 +36,7 @@ pub extern "C" fn cef_string_list_value(lt: *mut cef_string_list_t, index: c_int
         if index < 0 || lt.is_null() { return 0; }
         if index as usize > (*lt).len() - 1 { return 0; }
         let ref string = (*lt)[index as usize];
-        let utf16_chars: Vec<u16> = Utf16Encoder::new(string.chars()).collect();
+        let utf16_chars: Vec<u16> = string.encode_utf16().collect();
         cef_string_utf16_set(utf16_chars.as_ptr(), utf16_chars.len(), value, 1)
     }
 }
diff --git a/ports/cef/window.rs b/ports/cef/window.rs
index f84c0b90d1f..ee76ddd3035 100644
--- a/ports/cef/window.rs
+++ b/ports/cef/window.rs
@@ -14,7 +14,6 @@ use eutil::Downcast;
 use interfaces::CefApp;
 use interfaces::CefBrowser;
 use render_handler::CefRenderHandlerExtensions;
-use rustc_unicode::str::Utf16Encoder;
 use types::{cef_cursor_handle_t, cef_cursor_type_t, cef_rect_t};
 use wrappers::CefWrap;
 
@@ -331,10 +330,7 @@ impl WindowMethods for Window {
             Some(ref browser) => browser,
         };
         let str = match info {
-            Some(s) => {
-                let utf16_chars: Vec<u16> = Utf16Encoder::new(s.chars()).collect();
-                utf16_chars
-            }
+            Some(s) => s.encode_utf16().collect::<Vec<u16>>(),
             None => vec![]
         };
 
@@ -397,7 +393,7 @@ impl WindowMethods for Window {
         };
         if check_ptr_exist!(browser.get_host().get_client(), get_load_handler) &&
            check_ptr_exist!(browser.get_host().get_client().get_load_handler(), on_load_error) {
-            let utf16_chars: Vec<u16> = Utf16Encoder::new((url).chars()).collect();
+            let utf16_chars: Vec<u16> = url.encode_utf16().collect();
             browser.get_host()
                    .get_client()
                    .get_load_handler()
@@ -428,10 +424,7 @@ impl WindowMethods for Window {
         let frame = frame.downcast();
         let mut title_visitor = frame.title_visitor.borrow_mut();
         let str = match string {
-            Some(s) => {
-                let utf16_chars: Vec<u16> = Utf16Encoder::new(s.chars()).collect();
-                utf16_chars
-            }
+            Some(s) => s.encode_utf16().collect(),
             None => vec![]
         };
 
@@ -461,7 +454,7 @@ impl WindowMethods for Window {
         // FIXME(https://github.com/rust-lang/rust/issues/23338)
         let mut frame_url = servoframe.url.borrow_mut();
         *frame_url = url.into_string();
-        let utf16_chars: Vec<u16> = Utf16Encoder::new((*frame_url).chars()).collect();
+        let utf16_chars: Vec<u16> = frame_url.encode_utf16().collect();
         if check_ptr_exist!(browser.get_host().get_client(), get_display_handler) &&
            check_ptr_exist!(browser.get_host().get_client().get_display_handler(), on_address_change) {
             browser.get_host().get_client().get_display_handler().on_address_change((*browser).clone(), frame.clone(), utf16_chars.as_slice());
diff --git a/ports/cef/wrappers.rs b/ports/cef/wrappers.rs
index fdb2bb96063..e36820ce561 100644
--- a/ports/cef/wrappers.rs
+++ b/ports/cef/wrappers.rs
@@ -8,7 +8,6 @@ use interfaces::{cef_dialog_handler_t, cef_focus_handler_t};
 use interfaces::{cef_download_handler_t, cef_drag_handler_t, cef_context_menu_handler_t};
 use interfaces::{cef_geolocation_handler_t, cef_jsdialog_handler_t, cef_keyboard_handler_t};
 use interfaces::{cef_load_handler_t, cef_request_handler_t};
-use rustc_unicode::str::Utf16Encoder;
 use types::{cef_base_t, cef_browser_settings_t, CefBrowserSettings, cef_color_model_t};
 use types::{cef_context_menu_edit_state_flags_t};
 use types::{cef_context_menu_media_state_flags_t};
@@ -255,7 +254,7 @@ impl<'a,'b> CefWrap<*mut *const c_char> for &'a mut &'b str {
 
 impl<'a> CefWrap<cef_string_userfree_t> for String {
     fn to_c(string: String) -> cef_string_userfree_t {
-        let utf16_chars: Vec<u16> = Utf16Encoder::new(string.chars()).collect();
+        let utf16_chars: Vec<u16> = string.encode_utf16().collect();
 
         let boxed_string;
         unsafe {
diff --git a/tests/unit/style/lib.rs b/tests/unit/style/lib.rs
index e2c2bbe7e28..f2be3da2307 100644
--- a/tests/unit/style/lib.rs
+++ b/tests/unit/style/lib.rs
@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #![cfg(test)]
-#![feature(core_intrinsics, plugin, test)]
+#![feature(plugin, test)]
 
 extern crate app_units;
 extern crate cssparser;
diff --git a/tests/unit/style/viewport.rs b/tests/unit/style/viewport.rs
index 2ca9733afc2..026269421f7 100644
--- a/tests/unit/style/viewport.rs
+++ b/tests/unit/style/viewport.rs
@@ -51,13 +51,11 @@ fn test_meta_viewport<F>(meta: &str, callback: F)
     where F: Fn(&Vec<ViewportDescriptorDeclaration>, &str)
 {
     if let Some(mut rule) = ViewportRule::from_meta(meta) {
-        use std::intrinsics::discriminant_value;
-
         // from_meta uses a hash-map to collect the declarations, so we need to
         // sort them in a stable order for the tests
         rule.declarations.sort_by(|a, b| {
-            let a = unsafe { discriminant_value(&a.descriptor) };
-            let b = unsafe { discriminant_value(&b.descriptor) };
+            let a = a.descriptor.discriminant_value();
+            let b = b.descriptor.discriminant_value();
             a.cmp(&b)
         });