--- a/servo/components/style/properties/longhand/inherited_svg.mako.rs
+++ b/servo/components/style/properties/longhand/inherited_svg.mako.rs
@@ -35,17 +35,17 @@
     "fill", "SVGPaint",
     "::values::computed::SVGPaint::black()",
     products="gecko",
     animation_value_type="IntermediateSVGPaint",
     boxed=True,
     spec="https://www.w3.org/TR/SVG2/painting.html#SpecifyingFillPaint")}
 
 ${helpers.predefined_type("fill-opacity", "Opacity", "1.0",
-                          products="gecko", animation_value_type="none",
+                          products="gecko", animation_value_type="ComputedValue",
                           spec="https://www.w3.org/TR/SVG11/painting.html#FillOpacityProperty")}
 
 ${helpers.single_keyword("fill-rule", "nonzero evenodd",
                          gecko_enum_prefix="StyleFillRule",
                          gecko_inexhaustive=True,
                          products="gecko", animation_value_type="discrete",
                          spec="https://www.w3.org/TR/SVG11/painting.html#FillRuleProperty")}