Index: src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFWorkbook.java
===================================================================
--- src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFWorkbook.java	(revision 787414)
+++ src/ooxml/java/org/apache/poi/xssf/usermodel/XSSFWorkbook.java	(working copy)
@@ -215,6 +215,9 @@
      */
     private void onWorkbookCreate() {
         workbook = CTWorkbook.Factory.newInstance();
+        CTWorkbookPr workbookPr = CTWorkbookPr.Factory.newInstance();
+        workbookPr.setDate1904(false);
+        workbook.setWorkbookPr(workbookPr);
         CTBookViews bvs = workbook.addNewBookViews();
         CTBookView bv = bvs.addNewWorkbookView();
         bv.setActiveTab(0);