diff --git a/lib/dao.js b/lib/dao.js
index 45a3562f..1c0d809e 100644
--- a/lib/dao.js
+++ b/lib/dao.js
@@ -58,11 +58,11 @@ function copyData(from, to) {
   }
 }
 
-function convertDataPropertiesByType(data) {
+function convertSubsetOfPropertiesByType(inst, data) {
   var typedData = {};
   for (var key in data) {
     // Convert the properties by type
-    typedData[key] = data[key];
+    typedData[key] = inst[key];
     if (typeof typedData[key] === 'object'
             && typedData[key] !== null
             && typeof typedData[key].toObject === 'function') {
@@ -2523,7 +2523,7 @@ DataAccessObject.prototype.updateAttributes = function updateAttributes(data, op
         inst.trigger('save', function (saveDone) {
           inst.trigger('update', function (done) {
             copyData(data, inst);
-            var typedData = convertDataPropertiesByType(data);
+            var typedData = convertSubsetOfPropertiesByType(inst, data);
             context.data = typedData;
 
             function updateAttributesCallback(err) {