diff --git a/Demo/Program.cs b/Demo/Program.cs
index 2ea88b38c..477461f09 100644
--- a/Demo/Program.cs
+++ b/Demo/Program.cs
@@ -52,6 +52,7 @@ static void Main(string[] args)
             Demo11();
             Demo12();
             Demo13();
+            Demo14();
 
             /* ### PERFORMANCE TESTS ### */
             // # Use tests in this section to test the performance of NanoXLSX
@@ -576,6 +577,13 @@ private static void Demo13()
             wb2.Save();                                                                    // Save the workbook
         }
 
+        private static void Demo14()
+        {
+            Workbook wb = new Workbook("demo14fix.xlsx", "semicolon test");         // Create a new workbook
+            wb.CurrentWorksheet.AddCellFormula("IF(1=1;42;0)", "A1");
+            wb.Save();
+        }
+
         #region Utils
         /// <summary>
         /// Prints information about the passed cell
diff --git a/NanoXLSX/LowLevel/XlsxWriter.cs b/NanoXLSX/LowLevel/XlsxWriter.cs
index 8d0f81fb3..356b32087 100644
--- a/NanoXLSX/LowLevel/XlsxWriter.cs
+++ b/NanoXLSX/LowLevel/XlsxWriter.cs
@@ -940,7 +940,7 @@ private string CreateRowString(DynamicRow dynamicRow, Worksheet worksheet)
                     sb.Append("<c r=\"").Append(item.CellAddress).Append("\"").Append(typeDef).Append(styleDef).Append(">");
                     if (item.DataType == Cell.CellType.FORMULA)
                     {
-                        sb.Append("<f>").Append(EscapeXmlChars(item.Value.ToString())).Append("</f>");
+                        sb.Append("<f>").Append(EscapeXmlChars(item.Value.ToString(), sanitizeSemicolon: true)).Append("</f>");
                     }
                     else
                     {
@@ -1469,7 +1469,7 @@ private List<DynamicRow> GetSortedSheetData(Worksheet sheet)
         /// <param name="input">Input string to process</param>
         /// <returns>Escaped string</returns>
         /// <remarks>Note: The XML specs allow characters up to the character value of 0x10FFFF. However, the C# char range is only up to 0xFFFF. NanoXLSX will neglect all values above this level in the sanitizing check. Illegal characters like 0x1 will be replaced with a white space (0x20)</remarks>
-        public static string EscapeXmlChars(string input)
+        public static string EscapeXmlChars(string input, bool sanitizeSemicolon = false)
         {
             if (input == null) { return ""; }
             int len = input.Length;
@@ -1499,6 +1499,11 @@ public static string EscapeXmlChars(string input)
                     illegalCharacters.Add(i);
                     characterTypes.Add(3);
                 }
+                else if (input[i] == 0x3B && sanitizeSemicolon)
+                {
+                    illegalCharacters.Add(i);
+                    characterTypes.Add(4);
+                }
             }
             if (illegalCharacters.Count == 0)
             {
@@ -1527,6 +1532,10 @@ public static string EscapeXmlChars(string input)
                 {
                     sb.Append("&amp;");
                 }
+                else if (characterTypes[i] == 4 && sanitizeSemicolon) // replace ;
+                {
+                    sb.Append(",");
+                }
                 lastIndex = illegalCharacters[i] + 1;
             }
             sb.Append(input.Substring(lastIndex));