diff --git a/col.go b/col.go
index 8636566..cd9b5bf 100644
--- a/col.go
+++ b/col.go
@@ -169,8 +169,9 @@ type NumberCol struct {
 
 func (c *NumberCol) String(wb *WorkBook) []string {
 	if fNo := wb.Xfs[c.Index].formatNo(); fNo != 0 {
-		t := timeFromExcelTime(c.Float, wb.dateMode == 1)
-		return []string{yymmdd.Format(t, wb.Formats[fNo].str)}
+		  t := timeFromExcelTime(c.Float, wb.dateMode == 1)
+		  return []string{t.Format("2006-01-02 15:04:05")}
+		  //return []string{yymmdd.Format(t, wb.Formats[fNo].str)}
 	}
 	return []string{strconv.FormatFloat(c.Float, 'f', -1, 64)}
 }
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..697cbed
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,10 @@
+module github.com/jjavaruski/xls
+
+go 1.18
+
+require (
+	github.com/extrame/goyymmdd v0.0.0-20210114090516-7cc815f00d1a
+	github.com/extrame/ole2 v0.0.0-20160812065207-d69429661ad7
+	github.com/tealeg/xlsx v1.0.5
+	golang.org/x/text v0.3.7
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..88817f9
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,12 @@
+github.com/extrame/goyymmdd v0.0.0-20210114090516-7cc815f00d1a h1:c5k29baTzznteWs+9dxrtqpNxgtQ3V5NbU8d6laLK9Q=
+github.com/extrame/goyymmdd v0.0.0-20210114090516-7cc815f00d1a/go.mod h1:xbpgo9r3xURoPa/l3sLKLGcnWlkz9UkfFsQ7lW0S6h8=
+github.com/extrame/ole2 v0.0.0-20160812065207-d69429661ad7 h1:n+nk0bNe2+gVbRI8WRbLFVwwcBQ0rr5p+gzkKb6ol8c=
+github.com/extrame/ole2 v0.0.0-20160812065207-d69429661ad7/go.mod h1:GPpMrAfHdb8IdQ1/R2uIRBsNfnPnwsYE9YYI5WyY1zw=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/tealeg/xlsx v1.0.5 h1:+f8oFmvY8Gw1iUXzPk+kz+4GpbDZPK1FhPiQRd+ypgE=
+github.com/tealeg/xlsx v1.0.5/go.mod h1:btRS8dz54TDnvKNosuAqxrM1QgN1udgk9O34bDCnORM=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=