--- a/servo/components/style/stylesheets/document_rule.rs
+++ b/servo/components/style/stylesheets/document_rule.rs
@@ -1,26 +1,26 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 //! [@document rules](https://www.w3.org/TR/2012/WD-css3-conditional-20120911/#at-document)
 //! initially in CSS Conditional Rules Module Level 3, @document has been postponed to the level 4.
 //! We implement the prefixed `@-moz-document`.
 
-use cssparser::{Parser, Token, SourceLocation};
+use cssparser::{Parser, SourceLocation};
 #[cfg(feature = "gecko")]
 use malloc_size_of::{MallocSizeOfOps, MallocUnconditionalShallowSizeOf};
 use media_queries::Device;
 use parser::{Parse, ParserContext};
 use servo_arc::Arc;
 use shared_lock::{DeepCloneParams, DeepCloneWithLock, Locked, SharedRwLock, SharedRwLockReadGuard, ToCssWithGuard};
 use std::fmt::{self, Write};
 use str::CssStringWriter;
-use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
+use style_traits::{CssWriter, ParseError, ToCss};
 use stylesheets::CssRules;
 use values::CssUrl;
 
 #[derive(Debug)]
 /// A @-moz-document rule
 pub struct DocumentRule {
     /// The parsed condition
     pub condition: DocumentCondition,
@@ -98,48 +98,48 @@ pub enum UrlMatchingFunction {
     Regexp(String),
 }
 
 macro_rules! parse_quoted_or_unquoted_string {
     ($input:ident, $url_matching_function:expr) => {
         $input.parse_nested_block(|input| {
             let start = input.position();
             input.parse_entirely(|input| {
-                let location = input.current_source_location();
-                match *input.next()? {
-                    Token::QuotedString(ref value) => {
-                        Ok($url_matching_function(value.as_ref().to_owned()))
-                    },
-                    ref t => Err(location.new_unexpected_token_error(t.clone())),
-                }
+                let string = input.expect_string()?;
+                Ok($url_matching_function(string.as_ref().to_owned()))
             }).or_else(|_: ParseError| {
                 while let Ok(_) = input.next() {}
                 Ok($url_matching_function(input.slice_from(start).to_string()))
             })
         })
     }
 }
 
 impl UrlMatchingFunction {
     /// Parse a URL matching function for a`@document` rule's condition.
-    pub fn parse<'i, 't>(context: &ParserContext, input: &mut Parser<'i, 't>)
-        -> Result<UrlMatchingFunction, ParseError<'i>> {
+    pub fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
         if input.try(|input| input.expect_function_matching("url-prefix")).is_ok() {
-            parse_quoted_or_unquoted_string!(input, UrlMatchingFunction::UrlPrefix)
-        } else if input.try(|input| input.expect_function_matching("domain")).is_ok() {
-            parse_quoted_or_unquoted_string!(input, UrlMatchingFunction::Domain)
-        } else if input.try(|input| input.expect_function_matching("regexp")).is_ok() {
-            input.parse_nested_block(|input| {
+            return parse_quoted_or_unquoted_string!(input, UrlMatchingFunction::UrlPrefix)
+        }
+
+        if input.try(|input| input.expect_function_matching("domain")).is_ok() {
+            return parse_quoted_or_unquoted_string!(input, UrlMatchingFunction::Domain)
+        }
+
+        if input.try(|input| input.expect_function_matching("regexp")).is_ok() {
+            return input.parse_nested_block(|input| {
                 Ok(UrlMatchingFunction::Regexp(input.expect_string()?.as_ref().to_owned()))
-            })
-        } else if let Ok(url) = input.try(|input| CssUrl::parse(context, input)) {
-            Ok(UrlMatchingFunction::Url(url))
-        } else {
-            Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError))
+            });
         }
+
+        let url = CssUrl::parse(context, input)?;
+        Ok(UrlMatchingFunction::Url(url))
     }
 
     #[cfg(feature = "gecko")]
     /// Evaluate a URL matching function.
     pub fn evaluate(&self, device: &Device) -> bool {
         use gecko_bindings::bindings::Gecko_DocumentRule_UseForPresentation;
         use gecko_bindings::structs::URLMatchingFunction as GeckoUrlMatchingFunction;
         use nsstring::nsCStr;
@@ -177,21 +177,23 @@ impl UrlMatchingFunction {
 /// URL matching functions, and the condition evaluates to true whenever any
 /// one of those functions evaluates to true.
 #[css(comma)]
 #[derive(Clone, Debug, ToCss)]
 pub struct DocumentCondition(#[css(iterable)] Vec<UrlMatchingFunction>);
 
 impl DocumentCondition {
     /// Parse a document condition.
-    pub fn parse<'i, 't>(context: &ParserContext, input: &mut Parser<'i, 't>)
-        -> Result<Self, ParseError<'i>> {
+    pub fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
         input.parse_comma_separated(|input| UrlMatchingFunction::parse(context, input))
              .map(DocumentCondition)
     }
 
     /// Evaluate a document condition.
     pub fn evaluate(&self, device: &Device) -> bool {
-        self.0.iter().any(|ref url_matching_function|
+        self.0.iter().any(|url_matching_function| {
             url_matching_function.evaluate(device)
-        )
+        })
     }
 }