diff --git a/lib/timeline/component/ItemSet.js b/lib/timeline/component/ItemSet.js
index 46246144b..740fd5f0a 100644
--- a/lib/timeline/component/ItemSet.js
+++ b/lib/timeline/component/ItemSet.js
@@ -1538,12 +1538,12 @@ ItemSet.prototype._onDrag = function (event) {
 
     var me = this;
     var snap = this.options.snap || null;
-    var xOffset;
+    var xOffset = this.body.dom.root.getBoundingClientRect().left;
 
     if (this.options.rtl) {
-      xOffset = this.body.dom.root.offsetLeft + this.body.domProps.right.width;
+      xOffset += this.body.domProps.right.width;
     } else {
-      xOffset = this.body.dom.root.offsetLeft + this.body.domProps.left.width;
+      xOffset += this.body.domProps.left.width;
     }
 
     var scale = this.body.util.getScale();