diff --git a/lib/model-builder.js b/lib/model-builder.js
index 3519e943..7e6980a6 100644
--- a/lib/model-builder.js
+++ b/lib/model-builder.js
@@ -275,7 +275,7 @@ ModelBuilder.prototype.define = function defineClass(className, properties, sett
                 return new OrigDate(arg);
             };
         } else if(typeof DataType === 'string') {
-            DataType = dataSource.getSchemaType(DataType);
+            DataType = dataSource.resolveType(DataType);
         }
         
         if(prop.required) {
@@ -449,6 +449,46 @@ ModelBuilder.prototype.getSchemaName = function (name) {
     return 'AnonymousModel_' + this._nameCount;
 };
 
+/**
+ * Resolve the type string to be a function, for example, 'String' to String
+ * @param {String} type The type string, such as 'number', 'Number', 'boolean', or 'String'. It's case insensitive
+ * @returns {Function} if the type is resolved
+ */
+ModelBuilder.prototype.resolveType = function(type) {
+    if (!type) {
+        return type;
+    }
+    if (Array.isArray(type) && type.length > 0) {
+        // For array types, the first item should be the type string
+        var itemType = this.resolveType(type[0]);
+        if (typeof itemType === 'function') {
+            return [itemType];
+        }
+        else {
+            return itemType; // Not resolved, return the type string
+        }
+    }
+    if (typeof type === 'string') {
+        var schemaType = ModelBuilder.schemaTypes[type.toLowerCase()] || this.models[type];
+        if (schemaType) {
+            return schemaType;
+        } else {
+            return type;
+        }
+    } else if (type.constructor.name === 'Object') {
+        // We also support the syntax {type: 'string', ...}
+        if (type.type) {
+            return this.resolveType(type.type);
+        } else {
+            return this.define(this.getSchemaName(null),
+                type, {anonymous: true, idInjection: false});
+        }
+    } else if('function' === typeof type ) {
+        return type;
+    }
+    return type;
+};
+
 /**
  * Build models from dataSource definitions
  *
diff --git a/lib/model-definition.js b/lib/model-definition.js
index c57ad621..fb16dc2a 100644
--- a/lib/model-definition.js
+++ b/lib/model-definition.js
@@ -201,46 +201,6 @@ ModelDefinition.prototype.indexes = function () {
     return indexes;
 };
 
-/**
- * Resolve the type string to be a function, for example, 'String' to String
- * @param {String} type The type string, such as 'number', 'Number', 'boolean', or 'String'. It's case insensitive
- * @returns {Function} if the type is resolved
- */
-ModelDefinition.prototype.resolveType = function(type) {
-    if (!type) {
-        return type;
-    }
-    if (Array.isArray(type) && type.length > 0) {
-        // For array types, the first item should be the type string
-        var itemType = this.resolveType(type[0]);
-        if (typeof itemType === 'function') {
-            return [itemType];
-        }
-        else {
-            return itemType; // Not resolved, return the type string
-        }
-    }
-    if (typeof type === 'string') {
-        var schemaType = ModelDefinition.schemaTypes[type.toLowerCase()] || this.modelBuilder.models[type];
-        if (schemaType) {
-            return schemaType;
-        } else {
-            return type;
-        }
-    } else if (type.constructor.name === 'Object') {
-        // We also support the syntax {type: 'string', ...}
-        if (type.type) {
-            return this.resolveType(type.type);
-        } else {
-            return this.modelBuilder.define(this.modelBuilder.getSchemaName(null),
-                type, {anonymous: true, idInjection: false});
-        }
-    } else if('function' === typeof type ) {
-        return type;
-    }
-    return type;
-};
-
 /**
  * Build a model definition
  * @param {Boolean} force Forcing rebuild
@@ -257,7 +217,7 @@ ModelDefinition.prototype.build = function (forceRebuild) {
     this.properties = {};
     for (var p in this.rawProperties) {
         var prop = this.rawProperties[p];
-        var type = this.resolveType(prop);
+        var type = this.modelBuilder.resolveType(prop);
         if (typeof type === 'string') {
             this.associations.push({
                 source: this.name,