--- a/servo/components/style/properties/data.py
+++ b/servo/components/style/properties/data.py
@@ -229,16 +229,26 @@ class Shorthand(object):
 
         # https://drafts.csswg.org/css-animations/#keyframes
         # > The <declaration-list> inside of <keyframe-block> accepts any CSS property
         # > except those defined in this specification,
         # > but does accept the `animation-play-state` property and interprets it specially.
         self.allowed_in_keyframe_block = allowed_in_keyframe_block \
             and allowed_in_keyframe_block != "False"
 
+    def get_animatable(self):
+        animatable = False
+        for sub in self.sub_properties:
+            if sub.animatable:
+                animatable = True
+                break
+        return animatable
+
+    animatable = property(get_animatable)
+
 
 class Method(object):
     def __init__(self, name, return_type=None, arg_types=None, is_mut=False):
         self.name = name
         self.return_type = return_type
         self.arg_types = arg_types or []
         self.is_mut = is_mut
 

--- a/servo/components/style/properties/helpers/animated_properties.mako.rs
+++ b/servo/components/style/properties/helpers/animated_properties.mako.rs
@@ -190,31 +190,21 @@ impl TransitionProperty {
         }
     }
 }
 
 /// Returns true if this nsCSSPropertyID is one of the animatable properties.
 #[cfg(feature = "gecko")]
 pub fn nscsspropertyid_is_animatable(property: nsCSSPropertyID) -> bool {
     match property {
-        % for prop in data.longhands:
+        % for prop in data.longhands + data.shorthands_except_all():
             % if prop.animatable:
                 ${helpers.to_nscsspropertyid(prop.ident)} => true,
             % endif
         % endfor
-        % for prop in data.shorthands_except_all():
-            <%
-                animatable = "false"
-                for sub in prop.sub_properties:
-                    if sub.animatable:
-                        animatable = "true"
-                        break
-            %>
-            ${helpers.to_nscsspropertyid(prop.ident)} => ${animatable},
-        % endfor
         _ => false
     }
 }
 
 impl ToCss for TransitionProperty {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result
         where W: fmt::Write,
     {