--- a/servo/components/style/servo/selector_parser.rs
+++ b/servo/components/style/servo/selector_parser.rs
@@ -429,17 +429,17 @@ impl<'a> ::selectors::Parser for Selecto
         Ok(pseudo_element)
     }
 
     fn default_namespace(&self) -> Option<Namespace> {
         self.namespaces.default.clone().map(|(ns, _)| ns)
     }
 
     fn namespace_for_prefix(&self, prefix: &Prefix) -> Option<Namespace> {
-        self.namespaces.prefixes.get(prefix).cloned()
+        self.namespaces.prefixes.get(prefix).cloned().map(|(ns, _)| ns)
     }
 }
 
 impl SelectorImpl {
     /// Returns the pseudo-element cascade type of the given `pseudo`.
     #[inline]
     pub fn pseudo_element_cascade_type(pseudo: &PseudoElement) -> PseudoElementCascadeType {
         pseudo.cascade_type()

--- a/servo/components/style/stylesheets.rs
+++ b/servo/components/style/stylesheets.rs
@@ -1534,17 +1534,17 @@ fn register_namespace(ns: &Namespace) ->
     if id == -1 {
         Err(())
     } else {
         Ok(id as u32)
     }
 }
 
 #[cfg(feature = "servo")]
-fn register_namespace(ns: &Namespace) -> Result<u32, ()> {
+fn register_namespace(_: &Namespace) -> Result<u32, ()> {
     Ok(1) // servo doesn't use namespace ids
 }
 
 impl<'a> AtRuleParser for TopLevelRuleParser<'a> {
     type Prelude = AtRulePrelude;
     type AtRule = CssRule;
 
     fn parse_prelude(&mut self, name: &str, input: &mut Parser)