diff --git a/QXlsx/source/xlsxdocument.cpp b/QXlsx/source/xlsxdocument.cpp
index beb4e833..ea277b7e 100644
--- a/QXlsx/source/xlsxdocument.cpp
+++ b/QXlsx/source/xlsxdocument.cpp
@@ -491,7 +491,7 @@ bool DocumentPrivate::saveCsv(QString mainCSVFileName) const
         int maxRow = -1;
         int maxCol = -1;
 
-        currentSheet->workbook()->setActiveSheet(sheetIndexNumber);
+        currentSheet->workbook()->setActiveSheet(sheetIndexNumber++);
 
         auto wsheet = static_cast<Worksheet *>(currentSheet->workbook()->activeSheet());
         if (wsheet == nullptr) {