diff --git a/Services/Excel/classes/class.ilExcel.php b/Services/Excel/classes/class.ilExcel.php
index f7196a646e0a..c18ad81c2327 100644
--- a/Services/Excel/classes/class.ilExcel.php
+++ b/Services/Excel/classes/class.ilExcel.php
@@ -37,7 +37,26 @@ class ilExcel
     public const FORMAT_BIFF = "Xls";
     protected string $format;
 
-    private string $noncharacters = '[\uFFFE-\uFFFF\uFDD0-\uFDEF]';
+    private array $noncharacters = [
+        '\x{FFFE}-\x{FFFF}',
+        '\x{1FFFE}-\x{1FFFF}',
+        '\x{2FFFE}-\x{2FFFF}',
+        '\x{3FFFE}-\x{3FFFF}',
+        '\x{4FFFE}-\x{4FFFF}',
+        '\x{5FFFE}-\x{5FFFF}',
+        '\x{6FFFE}-\x{6FFFF}',
+        '\x{7FFFE}-\x{7FFFF}',
+        '\x{8FFFE}-\x{8FFFF}',
+        '\x{9FFFE}-\x{9FFFF}',
+        '\x{AFFFE}-\x{AFFFF}',
+        '\x{BFFFE}-\x{BFFFF}',
+        '\x{CFFFE}-\x{CFFFF}',
+        '\x{DFFFE}-\x{DFFFF}',
+        '\x{EFFFE}-\x{EFFFF}',
+        '\x{FFFFE}-\x{FFFFF}',
+        '\x{10FFFE}-\x{10FFFF}',
+        '\x{FDD0}-\x{FDEF}'
+    ];
 
     protected ilLanguage $lng;
     protected Spreadsheet $workbook;
@@ -570,6 +589,6 @@ public function mergeCells(string $coordinatesRange): void
 
     private function cleanupNonCharachters(string $string): string
     {
-        return mb_ereg_replace($this->noncharacters, '', $string);
+        return mb_ereg_replace('[' . implode('', $this->noncharacters) . ']', '', $string);
     }
 }