diff --git a/lib/datasource.js b/lib/datasource.js
index d854bd95..13f8c171 100644
--- a/lib/datasource.js
+++ b/lib/datasource.js
@@ -1251,12 +1251,12 @@ DataSource.prototype.idNames = function (modelName) {
  */
 DataSource.prototype.defineForeignKey = function defineForeignKey(className, key, foreignClassName) {
     // quit if key already defined
-    if (this.definitions[className].properties[key]) return;
+    if (this.definitions[className].rawProperties[key]) return;
 
     if (this.connector.defineForeignKey) {
         var cb = function (err, keyType) {
             if (err) throw err;
-            this.definitions[className].properties[key] = {type: keyType};
+            this.definitions[className].defineProperty(key, {type: keyType});
         }.bind(this);
         switch (this.connector.defineForeignKey.length) {
             case 4:
@@ -1268,7 +1268,7 @@ DataSource.prototype.defineForeignKey = function defineForeignKey(className, key
             break;
         }
     } else {
-        this.definitions[className].properties[key] = {type: Number};
+        this.definitions[className].defineProperty(key, {type: Number});
     }
     
     this.models[className].registerProperty(key);