diff --git a/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/Excel/XLWorkbook_Save.cs
index 3569a34..f64e9ba 100644
--- a/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -2027,7 +2027,7 @@
 
                 var ptfi = new PivotTableFieldInfo();
 
-                var fieldValueCells = source.Cells(cell => cell.Address.ColumnNumber == columnNumber
+                var fieldValueCells = source.CellsUsed(cell => cell.Address.ColumnNumber == columnNumber
                                                            && cell.Address.RowNumber > source.FirstRow().RowNumber());
                 var types = fieldValueCells.Select(cell => cell.DataType).Distinct();