diff --git a/components/style/properties/longhand/font.mako.rs b/components/style/properties/longhand/font.mako.rs
index 3a1fa19b87e..ff837bbaee4 100644
--- a/components/style/properties/longhand/font.mako.rs
+++ b/components/style/properties/longhand/font.mako.rs
@@ -411,7 +411,11 @@ ${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 = match self.value {
+                    1 => format!("\"{}\"", self.tag),
+                    0 => format!("\"{}\" off", self.tag),
+                    x => format!("\"{}\" {}", self.tag, x)
+                };
                 dest.write_str(&s)
             }
         }
diff --git a/tests/unit/style/parsing/font.rs b/tests/unit/style/parsing/font.rs
index bbf248ebe00..962e081ee20 100644
--- a/tests/unit/style/parsing/font.rs
+++ b/tests/unit/style/parsing/font.rs
@@ -70,10 +70,9 @@ fn font_feature_settings_should_throw_on_bad_input() {
 #[test]
 fn font_feature_settings_to_css() {
     assert_roundtrip_with_context!(font_feature_settings::parse, "normal");
-    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\"", "\"abcd\" 1");
-    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\" on", "\"abcd\" 1");
-    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\" off", "\"abcd\" 0");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\"");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\" on", "\"abcd\"");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\" off");
     assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\" 4");
-    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\", \"efgh\"",
-                                                                 "\"abcd\" 1, \"efgh\" 1");
+    assert_roundtrip_with_context!(font_feature_settings::parse, "\"abcd\", \"efgh\"");
 }