diff --git a/components/style/properties/gecko.mako.rs b/components/style/properties/gecko.mako.rs
index 3c4a45666b1..44b76f28b5a 100644
--- a/components/style/properties/gecko.mako.rs
+++ b/components/style/properties/gecko.mako.rs
@@ -1205,7 +1205,6 @@ impl Clone for ${style_struct.gecko_struct_name} {
     # Types used with predefined_type()-defined properties that we can auto-generate.
     predefined_types = {
         "length::NonNegativeLengthPercentageOrNormal": impl_style_coord,
-        "Length": impl_absolute_length,
         "MozScriptMinSize": impl_absolute_length,
         "RGBAColor": impl_rgba_color,
         "SVGLength": impl_svg_length,