diff --git a/components/style/gecko/pseudo_element_definition.mako.rs b/components/style/gecko/pseudo_element_definition.mako.rs
index 06323699b19..b507fafd865 100644
--- a/components/style/gecko/pseudo_element_definition.mako.rs
+++ b/components/style/gecko/pseudo_element_definition.mako.rs
@@ -112,7 +112,11 @@ impl PseudoElement {
             % for pseudo in PSEUDOS:
                 ${pseudo_element_variant(pseudo)} =>
                 % if pseudo.is_tree_pseudo_element():
-                    0,
+                    if unsafe { structs::StaticPrefs_sVarCache_layout_css_xul_tree_pseudos_content_enabled } {
+                        0
+                    } else {
+                        structs::CSS_PSEUDO_ELEMENT_ENABLED_IN_UA_SHEETS_AND_CHROME
+                    },
                 % elif pseudo.is_anon_box():
                     structs::CSS_PSEUDO_ELEMENT_ENABLED_IN_UA_SHEETS,
                 % else:
diff --git a/components/style/gecko/selector_parser.rs b/components/style/gecko/selector_parser.rs
index 61e282c1dce..4a5ae8aef64 100644
--- a/components/style/gecko/selector_parser.rs
+++ b/components/style/gecko/selector_parser.rs
@@ -488,7 +488,9 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
             }
             let args = args.into_boxed_slice();
             if let Some(pseudo) = PseudoElement::tree_pseudo_element(&name, args) {
-                return Ok(pseudo);
+                if self.is_pseudo_element_enabled(&pseudo) {
+                    return Ok(pseudo);
+                }
             }
         }
         Err(