diff --git a/components/style/properties/longhands/font.mako.rs b/components/style/properties/longhands/font.mako.rs
index 148b6fe33f6..b4b2ab0598c 100644
--- a/components/style/properties/longhands/font.mako.rs
+++ b/components/style/properties/longhands/font.mako.rs
@@ -80,7 +80,7 @@ ${helpers.predefined_type(
     engines="gecko",
     initial_value="computed::FontSizeAdjust::none()",
     initial_specified_value="specified::FontSizeAdjust::none()",
-    animation_value_type="ComputedValue",
+    animation_value_type="FontSizeAdjust",
     spec="https://drafts.csswg.org/css-fonts/#propdef-font-size-adjust",
 )}