diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
index c14f9df..e7c210e 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -372,8 +372,8 @@
                     WorksheetsInternal.Cast<XLWorksheet>().Where(w => w.SheetId == 0).OrderBy(w => w.Position))
             {
                 String rId = context.RelIdGenerator.GetNext(RelType.Workbook);
-                Int32 rIdSub = Int32.Parse(rId.Substring(3));
-                while (WorksheetsInternal.Cast<XLWorksheet>().Any(w => w.SheetId == rIdSub))
+                //Int32 rIdSub = Int32.Parse(rId.Substring(3));
+                while (WorksheetsInternal.Cast<XLWorksheet>().Any(w => w.SheetId == Int32.Parse(rId.Substring(3))))
                     rId = context.RelIdGenerator.GetNext(RelType.Workbook);
 
                 xlSheet.SheetId = Int32.Parse(rId.Substring(3));