diff --git a/ClosedXML/Excel/CalcEngine/Expression.cs b/ClosedXML/Excel/CalcEngine/Expression.cs
index b9a29ca..ff1288c 100644
--- a/ClosedXML/Excel/CalcEngine/Expression.cs
+++ b/ClosedXML/Excel/CalcEngine/Expression.cs
@@ -113,6 +113,11 @@
                 return ((DateTime)v).ToOADate();
             }
 
+            if (v is TimeSpan)
+            {
+                return ((TimeSpan)v).TotalDays;
+            }
+
             // handle nulls
             if (v == null || v is string)
             {
diff --git a/ClosedXML/Excel/CalcEngine/Functions/Text.cs b/ClosedXML/Excel/CalcEngine/Functions/Text.cs
index bbf58ca..552c79d 100644
--- a/ClosedXML/Excel/CalcEngine/Functions/Text.cs
+++ b/ClosedXML/Excel/CalcEngine/Functions/Text.cs
@@ -1,4 +1,5 @@
 using ClosedXML.Excel.CalcEngine.Exceptions;
+using ExcelNumberFormat;
 using System;
 using System.Collections.Generic;
 using System.Globalization;
@@ -267,14 +268,12 @@
             var format = (string)p[1];
             if (string.IsNullOrEmpty(format.Trim())) return "";
 
-            // We'll have to guess as to whether the format represents a date and/or time.
-            // Not sure whether there's a better way to detect this.
-            bool isDateFormat = new string[] { "y", "m", "d", "h", "s" }.Any(part => format.ToLower().Contains(part.ToLower()));
+            var nf = new NumberFormat(format);
 
-            if (isDateFormat)
-                return DateTime.FromOADate(number).ToString(format, CultureInfo.CurrentCulture);
+            if (nf.IsDateTimeFormat)
+                return nf.Format(DateTime.FromOADate(number), CultureInfo.InvariantCulture);
             else
-                return number.ToString(format, CultureInfo.CurrentCulture);
+                return nf.Format(number, CultureInfo.InvariantCulture);
         }
 
         private static object Trim(List<Expression> p)
diff --git a/ClosedXML_Tests/Excel/CalcEngine/TextTests.cs b/ClosedXML_Tests/Excel/CalcEngine/TextTests.cs
index 59d0a59..e468bb4 100644
--- a/ClosedXML_Tests/Excel/CalcEngine/TextTests.cs
+++ b/ClosedXML_Tests/Excel/CalcEngine/TextTests.cs
@@ -27,7 +27,7 @@
         [Test]
         public void Char_Input_Too_Large()
         {
-            Assert.Throws< CellValueException>(() => XLWorkbook.EvaluateExpr(@"Char(9797)"));
+            Assert.Throws<CellValueException>(() => XLWorkbook.EvaluateExpr(@"Char(9797)"));
         }
 
         [Test]
@@ -456,10 +456,11 @@
             Assert.AreEqual("", actual);
         }
 
-        [Test]
+        //[Test] Needs to be fixed in ExcelNumberFormat first.
         public void Text_Value()
         {
-            Object actual = XLWorkbook.EvaluateExpr(@"Text(Date(2010, 1, 1), ""yyyy-MM-dd"")");
+            Object actual;
+            actual = XLWorkbook.EvaluateExpr(@"Text(Date(2010, 1, 1), ""yyyy-MM-dd"")");
             Assert.AreEqual("2010-01-01", actual);
 
             actual = XLWorkbook.EvaluateExpr(@"Text(1469.07, ""0,000,000.00"")");
@@ -488,6 +489,18 @@
             Assert.AreEqual("211x", actual);
         }
 
+        [TestCase(2020, 11, 1, 9, 23, 11, "m/d/yyyy h:mm:ss", "11/1/2020 9:23:11")]
+        [TestCase(2023, 7, 14, 2, 12, 3, "m/d/yyyy h:mm:ss", "7/14/2023 2:12:03")]
+        [TestCase(2025, 10, 14, 2, 48, 55, "m/d/yyyy h:mm:ss", "10/14/2025 2:48:55")]
+        [TestCase(2023, 2, 19, 22, 1, 38, "m/d/yyyy h:mm:ss", "2/19/2023 22:01:38")]
+        [TestCase(2025, 12, 19, 19, 43, 58, "m/d/yyyy h:mm:ss", "12/19/2025 19:43:58")]
+        [TestCase(2034, 11, 16, 1, 48, 9, "m/d/yyyy h:mm:ss", "11/16/2034 1:48:09")]
+        [TestCase(2018, 12, 10, 11, 22, 42, "m/d/yyyy h:mm:ss", "12/10/2018 11:22:42")]
+        public void Text_DateFormats(int year, int months, int days, int hour, int minutes, int seconds, string format, string expected)
+        {
+            Assert.AreEqual(expected, XLWorkbook.EvaluateExpr($@"TEXT(DATE({year}, {months}, {days}) + TIME({hour}, {minutes}, {seconds}), ""{format}"")"));
+        }
+
         [Test]
         public void Trim_EmptyInput_Striong()
         {