diff --git a/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/Excel/XLWorkbook_Save.cs
index 16ce6fe..8f63530 100644
--- a/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -2157,7 +2157,7 @@
 
                 var df = new DataField
                 {
-                    Name = value.SourceName,
+                    Name = value.CustomName,
                     Field = (UInt32)sourceColumn.ColumnNumber() - 1,
                     Subtotal = value.SummaryFormula.ToOpenXml(),
                     ShowDataAs = value.Calculation.ToOpenXml(),