diff --git a/excelext/mapper.go b/excelext/mapper.go
index 88309ff..a250549 100644
--- a/excelext/mapper.go
+++ b/excelext/mapper.go
@@ -1,4 +1,4 @@
-package excelbuilder
+package excelext
 
 import (
 	"reflect"
@@ -78,7 +78,7 @@ func (em *ExcelMapper[T]) InitNewFile(sheetName string) (*excelize.File, error)
 
 func (em *ExcelMapper[T]) InitStyles(f *excelize.File) error {
 	styleDate, err := f.NewStyle(&excelize.Style{
-		CustomNumFmt: new("dd.mm.yyyy"),
+		CustomNumFmt: langext.Ptr("dd.mm.yyyy"),
 	})
 	if err != nil {
 		return err
diff --git a/excelext/utils.go b/excelext/utils.go
new file mode 100644
index 0000000..b82c1b1
--- /dev/null
+++ b/excelext/utils.go
@@ -0,0 +1,26 @@
+package excelext
+
+import (
+	"strconv"
+
+	"git.blackforestbytes.com/BlackForestBytes/goext/rfctime"
+	"github.com/360EntSecGroup-Skylar/excelize"
+)
+
+func c(row int, col int) string {
+	return excelize.ToAlphaString(col) + strconv.Itoa(row)
+}
+
+func excelizeOptTime(t *rfctime.RFC3339NanoTime) any {
+	if t == nil {
+		return ""
+	}
+	return t.Time()
+}
+
+func excelizeOptDate(t *rfctime.Date) any {
+	if t == nil {
+		return ""
+	}
+	return t.TimeUTC()
+}
diff --git a/goextVersion.go b/goextVersion.go
index 6b134a8..6d97a43 100644
--- a/goextVersion.go
+++ b/goextVersion.go
@@ -1,5 +1,5 @@
 package goext
 
-const GoextVersion = "0.0.629"
+const GoextVersion = "0.0.630"
 
-const GoextVersionTimestamp = "2026-03-14T14:09:13+0100"
+const GoextVersionTimestamp = "2026-03-14T14:10:09+0100"