diff --git a/src/signature_pad.js b/src/signature_pad.js
index f56605a4..5e2bee7f 100644
--- a/src/signature_pad.js
+++ b/src/signature_pad.js
@@ -42,7 +42,7 @@ var SignaturePad = (function (document) {
     SignaturePad.prototype.fromDataURL = function (dataUrl) {
         var self = this,
             image = new Image(),
-            ratio = window.devicePixelWidth || 1,
+            ratio = window.devicePixelRatio || 1,
             width = this._canvas.width / ratio,
             height = this._canvas.height / ratio;