diff --git a/ClosedXML/Excel/Cells/XLCell.cs b/ClosedXML/Excel/Cells/XLCell.cs
index 1338dad..87e2ac9 100644
--- a/ClosedXML/Excel/Cells/XLCell.cs
+++ b/ClosedXML/Excel/Cells/XLCell.cs
@@ -851,7 +851,7 @@
                     {
                         double dTest;
                         if (Double.TryParse(_cellValue, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out dTest))
-                            _cellValue = dTest.ToString(CultureInfo.InvariantCulture);
+                            _cellValue = dTest.ToInvariantString();
                         else
                         {
                             throw new ArgumentException(
@@ -865,7 +865,7 @@
                         if (_dataType == XLCellValues.Boolean)
                             _cellValue = (_cellValue != "0").ToString();
                         else if (_dataType == XLCellValues.TimeSpan)
-                            _cellValue = BaseDate.Add(GetTimeSpan()).ToOADate().ToString(CultureInfo.InvariantCulture);
+                            _cellValue = BaseDate.Add(GetTimeSpan()).ToOADate().ToInvariantString();
                     }
                 }
 
diff --git a/ClosedXML/Excel/DataValidation/XLDateCriteria.cs b/ClosedXML/Excel/DataValidation/XLDateCriteria.cs
index 792e6b0..8962b0a 100644
--- a/ClosedXML/Excel/DataValidation/XLDateCriteria.cs
+++ b/ClosedXML/Excel/DataValidation/XLDateCriteria.cs
@@ -12,51 +12,51 @@
 
         public void EqualTo(DateTime value)
         {
-            dataValidation.Value = value.ToOADate().ToString(CultureInfo.InvariantCulture);
+            dataValidation.Value = value.ToOADate().ToInvariantString();
             dataValidation.Operator = XLOperator.EqualTo;
         }
 
         public void NotEqualTo(DateTime value)
         {
-            dataValidation.Value = value.ToOADate().ToString(CultureInfo.InvariantCulture);
+            dataValidation.Value = value.ToOADate().ToInvariantString();
             dataValidation.Operator = XLOperator.NotEqualTo;
         }
 
         public void GreaterThan(DateTime value)
         {
-            dataValidation.Value = value.ToOADate().ToString(CultureInfo.InvariantCulture);
+            dataValidation.Value = value.ToOADate().ToInvariantString();
             dataValidation.Operator = XLOperator.GreaterThan;
         }
 
         public void LessThan(DateTime value)
         {
-            dataValidation.Value = value.ToOADate().ToString(CultureInfo.InvariantCulture);
+            dataValidation.Value = value.ToOADate().ToInvariantString();
             dataValidation.Operator = XLOperator.LessThan;
         }
 
         public void EqualOrGreaterThan(DateTime value)
         {
-            dataValidation.Value = value.ToOADate().ToString(CultureInfo.InvariantCulture);
+            dataValidation.Value = value.ToOADate().ToInvariantString();
             dataValidation.Operator = XLOperator.EqualOrGreaterThan;
         }
 
         public void EqualOrLessThan(DateTime value)
         {
-            dataValidation.Value = value.ToOADate().ToString(CultureInfo.InvariantCulture);
+            dataValidation.Value = value.ToOADate().ToInvariantString();
             dataValidation.Operator = XLOperator.EqualOrLessThan;
         }
 
         public void Between(DateTime minValue, DateTime maxValue)
         {
-            dataValidation.MinValue = minValue.ToOADate().ToString(CultureInfo.InvariantCulture);
-            dataValidation.MaxValue = maxValue.ToOADate().ToString(CultureInfo.InvariantCulture);
+            dataValidation.MinValue = minValue.ToOADate().ToInvariantString();
+            dataValidation.MaxValue = maxValue.ToOADate().ToInvariantString();
             dataValidation.Operator = XLOperator.Between;
         }
 
         public void NotBetween(DateTime minValue, DateTime maxValue)
         {
-            dataValidation.MinValue = minValue.ToOADate().ToString(CultureInfo.InvariantCulture);
-            dataValidation.MaxValue = maxValue.ToOADate().ToString(CultureInfo.InvariantCulture);
+            dataValidation.MinValue = minValue.ToOADate().ToInvariantString();
+            dataValidation.MaxValue = maxValue.ToOADate().ToInvariantString();
             dataValidation.Operator = XLOperator.NotBetween;
         }
     }
diff --git a/ClosedXML/Excel/Ranges/XLRangeAddress.cs b/ClosedXML/Excel/Ranges/XLRangeAddress.cs
index d5b0e94..ddf27f4 100644
--- a/ClosedXML/Excel/Ranges/XLRangeAddress.cs
+++ b/ClosedXML/Excel/Ranges/XLRangeAddress.cs
@@ -65,7 +65,7 @@
                 else
                 {
                     FirstAddress = XLAddress.Create(worksheet, firstPart + "1");
-                    LastAddress = XLAddress.Create(worksheet, secondPart + XLHelper.MaxRowNumber.ToString(CultureInfo.InvariantCulture));    
+                    LastAddress = XLAddress.Create(worksheet, secondPart + XLHelper.MaxRowNumber.ToInvariantString());
                 }
             }
 
diff --git a/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/Excel/XLWorkbook_Save.cs
index acf1831..19fdd69 100644
--- a/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -1640,7 +1640,7 @@
                 {
                     var vTDouble1 = new VTDouble
                     {
-                        Text = p.GetValue<Double>().ToString(CultureInfo.InvariantCulture)
+                        Text = p.GetValue<Double>().ToInvariantString()
                     };
                     customDocumentProperty.AppendChild(vTDouble1);
                 }
@@ -2381,10 +2381,10 @@
             var dm = ds.Margins;
             if (!dm.Automatic)
                 retVal.Inset = String.Format("{0}in,{1}in,{2}in,{3}in",
-                    dm.Left.ToString(CultureInfo.InvariantCulture),
-                    dm.Top.ToString(CultureInfo.InvariantCulture),
-                    dm.Right.ToString(CultureInfo.InvariantCulture),
-                    dm.Bottom.ToString(CultureInfo.InvariantCulture));
+                    dm.Left.ToInvariantString(),
+                    dm.Top.ToInvariantString(),
+                    dm.Right.ToInvariantString(),
+                    dm.Bottom.ToInvariantString());
 
             return retVal;
         }
@@ -2440,10 +2440,10 @@
             sb.Append(";");
 
             sb.Append("width:");
-            sb.Append(Math.Round(c.Style.Size.Width * 7.5, 2).ToString(CultureInfo.InvariantCulture));
+            sb.Append(Math.Round(c.Style.Size.Width * 7.5, 2).ToInvariantString());
             sb.Append("pt;");
             sb.Append("height:");
-            sb.Append(Math.Round(c.Style.Size.Height, 2).ToString(CultureInfo.InvariantCulture));
+            sb.Append(Math.Round(c.Style.Size.Height, 2).ToInvariantString());
             sb.Append("pt;");
 
             sb.Append("z-index:");
@@ -3913,7 +3913,7 @@
                                 var timeSpan = opCell.GetTimeSpan();
                                 var cellValue = new CellValue();
                                 cellValue.Text =
-                                    XLCell.BaseDate.Add(timeSpan).ToOADate().ToString(CultureInfo.InvariantCulture);
+                                    XLCell.BaseDate.Add(timeSpan).ToOADate().ToInvariantString();
                                 cell.CellValue = cellValue;
                             }
                             else if (dataType == XLCellValues.DateTime || dataType == XLCellValues.Number)
@@ -3921,7 +3921,7 @@
                                 if (!XLHelper.IsNullOrWhiteSpace(opCell.InnerText))
                                 {
                                     var cellValue = new CellValue();
-                                    cellValue.Text = Double.Parse(opCell.InnerText, XLHelper.NumberStyle, XLHelper.ParseCulture).ToString(CultureInfo.InvariantCulture);
+                                    cellValue.Text = Double.Parse(opCell.InnerText, XLHelper.NumberStyle, XLHelper.ParseCulture).ToInvariantString();
                                     cell.CellValue = cellValue;
                                 }
                             }