diff --git a/src/PhpSpreadsheet/Spreadsheet.php b/src/PhpSpreadsheet/Spreadsheet.php
index f45b7e87..db617ef6 100644
--- a/src/PhpSpreadsheet/Spreadsheet.php
+++ b/src/PhpSpreadsheet/Spreadsheet.php
@@ -506,6 +506,7 @@ class Spreadsheet
         $this->disconnectWorksheets();
         $this->calculationEngine = null;
         $this->cellXfCollection = [];
+        $this->cellStyleXfCollection = [];
     }
 
     /**