diff --git a/components/script/dom/cssrule.rs b/components/script/dom/cssrule.rs
index 5945123ac51..853a9c9b643 100644
--- a/components/script/dom/cssrule.rs
+++ b/components/script/dom/cssrule.rs
@@ -106,6 +106,7 @@ impl CSSRule {
             StyleCssRule::Page(_) => unreachable!(),
             StyleCssRule::Document(_) => unimplemented!(), // TODO
             StyleCssRule::Layer(_) => unimplemented!(),    // TODO
+            StyleCssRule::ScrollTimeline(_) => unimplemented!(), // TODO
         }
     }
 
diff --git a/components/style/stylesheets/rule_parser.rs b/components/style/stylesheets/rule_parser.rs
index fe4988044d3..40ae7fb6188 100644
--- a/components/style/stylesheets/rule_parser.rs
+++ b/components/style/stylesheets/rule_parser.rs
@@ -477,6 +477,7 @@ impl<'a, 'b, 'i> AtRuleParser<'i> for NestedRuleParser<'a, 'b> {
                 let cond = DocumentCondition::parse(self.context, input)?;
                 AtRulePrelude::Document(cond)
             },
+            #[cfg(feature = "gecko")]
             "scroll-timeline" if static_prefs::pref!("layout.css.scroll-linked-animations.enabled") => {
                 let name = TimelineName::parse(self.context, input)?;
                 AtRulePrelude::ScrollTimeline(name)