diff --git a/src/drag/index.js b/src/drag/index.js
index 8b6facd..605b93e 100644
--- a/src/drag/index.js
+++ b/src/drag/index.js
@@ -7,7 +7,8 @@ class Drag extends Component {
     overflow: false,
     limit: 'window',
     'disable-x': false,
-    'disable-y': false
+    'disable-y': false,
+    by: String
   }
 }