diff --git a/src/Spout/Writer/Common/Entity/Worksheet.php b/src/Spout/Writer/Common/Entity/Worksheet.php
index d2c66a4..c2fdd80 100644
--- a/src/Spout/Writer/Common/Entity/Worksheet.php
+++ b/src/Spout/Writer/Common/Entity/Worksheet.php
@@ -186,7 +186,7 @@ class Worksheet
      */
     public function getColWidthXML()
     {
-        if (empty($colWidths)) {
+        if (empty($this->colWidths)) {
             return '';
         }
         $xml = '<cols>';