diff --git a/components/style/properties/longhands/font.mako.rs b/components/style/properties/longhands/font.mako.rs
index 098cb06b3a6..d65afad693d 100644
--- a/components/style/properties/longhands/font.mako.rs
+++ b/components/style/properties/longhands/font.mako.rs
@@ -412,7 +412,7 @@ ${helpers.predefined_type(
                         is_system_font: true,
                     },
                     font_size: FontSize {
-                        size: Au(system.size).into(),
+                        size: cx.maybe_zoom_text(Au(system.size).into()),
                         keyword_info: None
                     },
                     font_weight,