diff --git a/components/script/dom/cssrule.rs b/components/script/dom/cssrule.rs
index 9a0a2e3060c..cea98258786 100644
--- a/components/script/dom/cssrule.rs
+++ b/components/script/dom/cssrule.rs
@@ -105,6 +105,7 @@ impl CSSRule {
             StyleCssRule::Viewport(_) => unimplemented!(),  // TODO
             StyleCssRule::LayerBlock(_) => unimplemented!(), // TODO
             StyleCssRule::LayerStatement(_) => unimplemented!(), // TODO
+            StyleCssRule::FontPaletteValues(_) => unimplemented!(), // TODO
         }
     }
 
diff --git a/components/style/stylesheets/rule_parser.rs b/components/style/stylesheets/rule_parser.rs
index 9fe2d0c87e9..1fd2d20aa4d 100644
--- a/components/style/stylesheets/rule_parser.rs
+++ b/components/style/stylesheets/rule_parser.rs
@@ -503,6 +503,7 @@ impl<'a, 'b, 'i> AtRuleParser<'i> for NestedRuleParser<'a, 'b> {
                 let family_names = parse_family_name_list(self.context, input)?;
                 AtRulePrelude::FontFeatureValues(family_names)
             },
+            #[cfg(feature = "gecko")]
             "font-palette-values" if static_prefs::pref!("layout.css.font-palette.enabled") => {
                 let name = DashedIdent::parse(self.context, input)?;
                 AtRulePrelude::FontPaletteValues(name)