diff --git a/components/style/gecko/generated/pseudo_element_definition.rs b/components/style/gecko/generated/pseudo_element_definition.rs
index 4f627fe9459..224ef0ce480 100644
--- a/components/style/gecko/generated/pseudo_element_definition.rs
+++ b/components/style/gecko/generated/pseudo_element_definition.rs
@@ -176,12 +176,14 @@ pub enum PseudoElement {
 
 
 /// The number of eager pseudo-elements.
-pub const EAGER_PSEUDO_COUNT: usize = 2;
+pub const EAGER_PSEUDO_COUNT: usize = 4;
 
 /// The list of eager pseudos.
 pub const EAGER_PSEUDOS: [PseudoElement; EAGER_PSEUDO_COUNT] = [
     PseudoElement::Before,
     PseudoElement::After,
+    PseudoElement::FirstLine,
+    PseudoElement::FirstLetter,
 ];
 
 impl PseudoElement {
@@ -458,7 +460,7 @@ impl PseudoElement {
     #[inline]
     pub fn is_eager(&self) -> bool {
         matches!(*self,
-                 PseudoElement::Before | PseudoElement::After)
+                 PseudoElement::Before | PseudoElement::After | PseudoElement::FirstLine | PseudoElement::FirstLetter)
     }
 
     /// Gets the flags associated to this pseudo-element, or 0 if it's an
diff --git a/components/style/gecko/pseudo_element_definition.mako.rs b/components/style/gecko/pseudo_element_definition.mako.rs
index 81bf539f2e1..77ac1e0f1fb 100644
--- a/components/style/gecko/pseudo_element_definition.mako.rs
+++ b/components/style/gecko/pseudo_element_definition.mako.rs
@@ -11,7 +11,7 @@ pub enum PseudoElement {
     % endfor
 }
 
-<% EAGER_PSEUDOS = ["Before", "After"] %>
+<% EAGER_PSEUDOS = ["Before", "After", "FirstLine", "FirstLetter"] %>
 
 /// The number of eager pseudo-elements.
 pub const EAGER_PSEUDO_COUNT: usize = ${len(EAGER_PSEUDOS)};