diff --git a/src/lib/template/templatizer.html b/src/lib/template/templatizer.html
index d06cc4c2..0b6cf5d3 100644
--- a/src/lib/template/templatizer.html
+++ b/src/lib/template/templatizer.html
@@ -299,6 +299,8 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
     _extendTemplate: function(template, proto) {
       var n$ = Object.getOwnPropertyNames(proto);
       if (proto._propertySetter) {
+        // _propertySetter API may need to be copied onto the template,
+        // and it needs to come first to allow the property swizzle below
         template._propertySetter = proto._propertySetter;
       }
       for (var i=0, n; (i<n$.length) && (n=n$[i]); i++) {