diff --git a/components/style/gecko/non_ts_pseudo_class_list.rs b/components/style/gecko/non_ts_pseudo_class_list.rs
index f7d8be418de..cf21cbf8999 100644
--- a/components/style/gecko/non_ts_pseudo_class_list.rs
+++ b/components/style/gecko/non_ts_pseudo_class_list.rs
@@ -37,7 +37,7 @@ macro_rules! apply_non_ts_list {
                 ("visited", Visited, visited, IN_VISITED_STATE, _),
                 ("active", Active, active, IN_ACTIVE_STATE, _),
                 ("checked", Checked, checked, IN_CHECKED_STATE, _),
-                ("defined", Defined, defined, IN_DEFINED_STATE, PSEUDO_CLASS_ENABLED_IN_UA_SHEETS_AND_CHROME),
+                ("defined", Defined, defined, IN_DEFINED_STATE, _),
                 ("disabled", Disabled, disabled, IN_DISABLED_STATE, _),
                 ("enabled", Enabled, enabled, IN_ENABLED_STATE, _),
                 ("focus", Focus, focus, IN_FOCUS_STATE, _),
diff --git a/components/style/gecko/selector_parser.rs b/components/style/gecko/selector_parser.rs
index 039c069d2bb..1871d60a0b2 100644
--- a/components/style/gecko/selector_parser.rs
+++ b/components/style/gecko/selector_parser.rs
@@ -178,9 +178,6 @@ impl NonTSPseudoClass {
             NonTSPseudoClass::Fullscreen => unsafe {
                 mozilla::StaticPrefs_sVarCache_full_screen_api_unprefix_enabled
             },
-            NonTSPseudoClass::Defined => unsafe {
-                structs::nsContentUtils_sIsCustomElementsEnabled
-            },
             // Otherwise, a pseudo-class is enabled in content when it
             // doesn't have any enabled flag.
             _ => !self