diff --git a/components/style/properties/longhand/font.mako.rs b/components/style/properties/longhand/font.mako.rs
index 435a4dafc6a..4f13603a0fb 100644
--- a/components/style/properties/longhand/font.mako.rs
+++ b/components/style/properties/longhand/font.mako.rs
@@ -411,15 +411,22 @@ ${helpers.single_keyword("font-variant-position",
 
         impl ToCss for FeatureTagValue {
             fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-                let s = format!("{} {}", self.tag, self.value);
+                let s = format!("\"{}\" {}", self.tag, self.value);
                 dest.write_str(&s)
             }
         }
 
         impl FeatureTagValue {
+            /// <string> [ on | off | <integer> ]
             pub fn parse(input: &mut Parser) -> Result<FeatureTagValue, ()> {
                 let tag = try!(input.expect_string()).into_owned();
 
+                // allowed strings of length 4 containing chars: <U+20, U+7E>
+                if tag.len() != 4 ||
+                   tag.chars().any(|c| c < ' ' || c > '~') {
+                       return Err(())
+                   }
+
                 if let Ok(value) = input.try(|input| input.expect_integer()) {
                     // handle integer, throw if it is negative
                     if value >= 0 {
@@ -427,11 +434,14 @@ ${helpers.single_keyword("font-variant-position",
                     } else {
                         Err(())
                     }
+                } else if let Ok(_) = input.try(|input| input.expect_ident_matching("on")) {
+                    // on is an alias for '1'
+                    Ok(FeatureTagValue{ tag: tag, value: 1 })
                 } else if let Ok(_) = input.try(|input| input.expect_ident_matching("off")) {
                     // off is an alias for '0'
                     Ok(FeatureTagValue{ tag: tag, value: 0 })
                 } else {
-                    // remainders (empty value and "on" keyword) are aliases for '1'
+                    // empty value is an alias for '1'
                     Ok(FeatureTagValue{ tag:tag, value: 1 })
                 }
             }
@@ -443,13 +453,13 @@ ${helpers.single_keyword("font-variant-position",
         computed_value::T::Normal
     }
 
+    /// normal | <feature-tag-value>#
     pub fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
         if input.try(|input| input.expect_ident_matching("normal")).is_ok() {
             Ok(computed_value::T::Normal)
         } else {
-            input.parse_comma_separated(|input| {
-                computed_value::FeatureTagValue::parse(input)
-            }).map(computed_value::T::Computed)
+            input.parse_comma_separated(computed_value::FeatureTagValue::parse)
+                 .map(computed_value::T::Computed)
         }
     }
 </%helpers:longhand>
diff --git a/tests/unit/style/parsing/font.rs b/tests/unit/style/parsing/font.rs
new file mode 100644
index 00000000000..68eda7b901b
--- /dev/null
+++ b/tests/unit/style/parsing/font.rs
@@ -0,0 +1,43 @@
+/* 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/. */
+
+use cssparser::Parser;
+use media_queries::CSSErrorReporterTest;
+use style::parser::ParserContext;
+use style::stylesheets::Origin;
+use url::Url;
+
+#[test]
+fn font_feature_settings_should_parse_properly() {
+    use style::properties::longhands::font_feature_settings;
+    use style::properties::longhands::font_feature_settings::computed_value;
+    use style::properties::longhands::font_feature_settings::computed_value::FeatureTagValue;
+
+    let normal = parse_longhand!(font_feature_settings, "normal");
+    let normal_computed = computed_value::T::Normal;
+    assert_eq!(normal, normal_computed);
+
+    let on = parse_longhand!(font_feature_settings, "\"abcd\" on");
+    let on_computed = computed_value::T::Computed(vec![FeatureTagValue{ tag:String::from("abcd"), value: 1 }]);
+    assert_eq!(on, on_computed);
+
+    let off = parse_longhand!(font_feature_settings, "\"abcd\" off");
+    let off_computed = computed_value::T::Computed(vec![FeatureTagValue{ tag:String::from("abcd"), value: 0 }]);
+    assert_eq!(off, off_computed);
+
+    let empty = parse_longhand!(font_feature_settings, "\"abcd\"");
+    let empty_computed = computed_value::T::Computed(vec![FeatureTagValue{ tag:String::from("abcd"), value: 1 }]);
+    assert_eq!(empty, empty_computed);
+
+    let pos_integer = parse_longhand!(font_feature_settings, "\"abcd\" 100");
+    let pos_integer_computed = computed_value::T::Computed(vec![FeatureTagValue{ tag:String::from("abcd"), value: 100 }]);
+    assert_eq!(pos_integer, pos_integer_computed);
+
+    let pos_integer = parse_longhand!(font_feature_settings, "\"abcd\" off, \"efgh\"");
+    let pos_integer_computed = computed_value::T::Computed(vec![
+        FeatureTagValue{ tag:String::from("abcd"), value: 0 },
+        FeatureTagValue{ tag:String::from("efgh"), value: 1 }
+    ]);
+    assert_eq!(pos_integer, pos_integer_computed);
+}
diff --git a/tests/unit/style/parsing/mod.rs b/tests/unit/style/parsing/mod.rs
index c481ea865da..f9d932b8346 100644
--- a/tests/unit/style/parsing/mod.rs
+++ b/tests/unit/style/parsing/mod.rs
@@ -62,6 +62,7 @@ macro_rules! parse_longhand {
 }
 
 mod basic_shape;
+mod font;
 mod image;
 mod mask;
 mod position;