diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/CalcEngine/Functions/Text.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/CalcEngine/Functions/Text.cs
index 4bec9d0..0da3a1a 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/CalcEngine/Functions/Text.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/CalcEngine/Functions/Text.cs
@@ -78,12 +78,15 @@
         }
         static object Left(List<Expression> p)
         {
+            var str = (string)p[0];
             var n = 1;
             if (p.Count > 1)
             {
                 n = (int)p[1];
             }
-            return ((string)p[0]).Substring(0, n);
+            if (n >= str.Length) return str;
+
+            return str.Substring(0, n);
         }
         static object Len(List<Expression> p)
         {
@@ -95,7 +98,14 @@
         }
         static object Mid(List<Expression> p)
         {
-            return ((string)p[0]).Substring((int)p[1] - 1, (int)p[2]);
+            var str = (string)p[0];
+            var start = (int)p[1] - 1;
+            var length = (int)p[2];
+            if (start > str.Length - 1)
+                return String.Empty;
+            if (start + length > str.Length - 1)
+                return str.Substring(start);
+            return str.Substring(start, length);
         }
         static object Proper(List<Expression> p)
         {
@@ -129,13 +139,16 @@
         }
         static object Right(List<Expression> p)
         {
+            var str = (string)p[0];
             var n = 1;
             if (p.Count > 1)
             {
                 n = (int)p[1];
             }
-            var s = (string)p[0];
-            return s.Substring(s.Length - n);
+            
+            if (n >= str.Length) return str;
+
+            return str.Substring(str.Length - n);
         }
         static object Search(List<Expression> p)
         {
diff --git a/ClosedXML/ClosedXML/ClosedXML_Tests/ClosedXML_Tests.csproj b/ClosedXML/ClosedXML/ClosedXML_Tests/ClosedXML_Tests.csproj
index 2c0741b..3872960 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Tests/ClosedXML_Tests.csproj
+++ b/ClosedXML/ClosedXML/ClosedXML_Tests/ClosedXML_Tests.csproj
@@ -114,6 +114,7 @@
     <Compile Include="Examples\RowsTests.cs" />
     <Compile Include="Examples\StylesTests.cs" />
     <Compile Include="ExcelDocsComparerTests.cs" />
+    <Compile Include="Excel\CalcEngine\TextTests.cs" />
     <Compile Include="XLHelperTests.cs" />
     <Compile Include="Excel\AutoFilters\AutoFilterTests.cs" />
     <Compile Include="Excel\CalcEngine\DateAndTimeTests.cs" />
diff --git a/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/CalcEngine/TextTests.cs b/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/CalcEngine/TextTests.cs
new file mode 100644
index 0000000..ebb55e9
--- /dev/null
+++ b/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/CalcEngine/TextTests.cs
@@ -0,0 +1,96 @@
+using System;
+using ClosedXML.Excel;
+using NUnit.Framework;
+
+namespace ClosedXML_Tests.Excel.CalcEngine
+{
+    [TestFixture]
+    public class TextTests
+    {
+        [Test]
+        public void Left_Default()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Left(""ABC"")");
+            Assert.AreEqual("A", actual);
+        }
+
+        [Test]
+        public void Left_Value()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Left(""ABC"", 2)");
+            Assert.AreEqual("AB", actual);
+        }
+
+        [Test]
+        public void Left_BiggerThanLength()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Left(""ABC"", 5)");
+            Assert.AreEqual("ABC", actual);
+        }
+
+        [Test]
+        public void Left_Empty()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Left("""")");
+            Assert.AreEqual("", actual);
+        }
+
+        [Test]
+        public void Right_Default()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Right(""ABC"")");
+            Assert.AreEqual("C", actual);
+        }
+
+        [Test]
+        public void Right_Value()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Right(""ABC"", 2)");
+            Assert.AreEqual("BC", actual);
+        }
+
+        [Test]
+        public void Right_BiggerThanLength()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Right(""ABC"", 5)");
+            Assert.AreEqual("ABC", actual);
+        }
+
+        [Test]
+        public void Right_Empty()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Right("""")");
+            Assert.AreEqual("", actual);
+        }
+
+
+        
+        [Test]
+        public void Mid_Value()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Mid(""ABC"", 2, 2)");
+            Assert.AreEqual("BC", actual);
+        }
+
+        [Test]
+        public void Mid_BiggerThanLength()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Mid(""ABC"", 1, 5)");
+            Assert.AreEqual("ABC", actual);
+        }
+
+        [Test]
+        public void Mid_StartAfter()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Mid(""ABC"", 5, 5)");
+            Assert.AreEqual("", actual);
+        }
+
+        [Test]
+        public void Mid_Empty()
+        {
+            Object actual = XLWorkbook.EvaluateExpr(@"Mid("""", 1, 1)");
+            Assert.AreEqual("", actual);
+        }
+    }
+}
\ No newline at end of file