diff --git a/ClosedXML/ClosedXML/ClosedXML/ExcelHelper.cs b/ClosedXML/ClosedXML/ClosedXML/ExcelHelper.cs
index 8338961..cb4a863 100644
--- a/ClosedXML/ClosedXML/ClosedXML/ExcelHelper.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/ExcelHelper.cs
@@ -84,12 +84,33 @@
 
         public static bool IsValidColumn(string column)
         {
-            if (StringExtensions.IsNullOrWhiteSpace(column) || column.Length > 3)
+            Int32 length = column.Length;
+            if (StringExtensions.IsNullOrWhiteSpace(column) || length > 3)
                 return false;
 
             String theColumn = column.ToUpper();
-            return
-                !column.Where((t, i) => theColumn[i] < 'A' || theColumn[i] > 'Z' || (i == 2 && theColumn[i] > 'D')).Any();
+
+            
+            Boolean isValid = theColumn[0] >= 'A' && theColumn[0] <= 'Z';
+            if (length == 1)
+                return isValid;
+
+            if (length == 2)
+                return isValid && theColumn[1] >= 'A' && theColumn[1] <= 'Z';
+
+            if (theColumn[0] < 'X')
+                return theColumn[1] >= 'A' && theColumn[1] <= 'Z'
+                    && theColumn[2] >= 'A' && theColumn[2] <= 'Z';
+            
+            if (theColumn[0] != 'X') return false;
+
+            if (theColumn[1] < 'F')
+                return theColumn[2] >= 'A' && theColumn[2] <= 'Z';
+
+            if (theColumn[1] != 'F') return false;
+
+            return theColumn[2] >= 'A' && theColumn[2] <= 'D';
+
         }
 
         public static bool IsValidRow(string rowString)
diff --git a/ClosedXML/ClosedXML/ClosedXML_Tests/ClosedXML_Tests.csproj b/ClosedXML/ClosedXML/ClosedXML_Tests/ClosedXML_Tests.csproj
index 8fe2609..9eb6264 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Tests/ClosedXML_Tests.csproj
+++ b/ClosedXML/ClosedXML/ClosedXML_Tests/ClosedXML_Tests.csproj
@@ -71,6 +71,7 @@
     <Compile Include="Examples\RowsTests.cs" />
     <Compile Include="Examples\StylesTests.cs" />
     <Compile Include="ExcelDocsComparerTests.cs" />
+    <Compile Include="ExcelHelperTest.cs" />
     <Compile Include="Excel\AutoFilters\AutoFilterTests.cs" />
     <Compile Include="Excel\Cells\XLCellTest.cs" />
     <Compile Include="Excel\Columns\ColumnsTests.cs" />
diff --git a/ClosedXML/ClosedXML/ClosedXML_Tests/ExcelHelperTest.cs b/ClosedXML/ClosedXML/ClosedXML_Tests/ExcelHelperTest.cs
new file mode 100644
index 0000000..e49320f
--- /dev/null
+++ b/ClosedXML/ClosedXML/ClosedXML_Tests/ExcelHelperTest.cs
@@ -0,0 +1,89 @@
+using ClosedXML.Excel;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System;
+
+namespace ClosedXML_Tests
+{
+    
+    
+    /// <summary>
+    ///This is a test class for ExcelHelperTest and is intended
+    ///to contain all ExcelHelperTest Unit Tests
+    ///</summary>
+    [TestClass()]
+    public class ExcelHelperTest
+    {
+
+
+        private TestContext testContextInstance;
+
+        /// <summary>
+        ///Gets or sets the test context which provides
+        ///information about and functionality for the current test run.
+        ///</summary>
+        public TestContext TestContext
+        {
+            get
+            {
+                return testContextInstance;
+            }
+            set
+            {
+                testContextInstance = value;
+            }
+        }
+
+        #region Additional test attributes
+        // 
+        //You can use the following additional attributes as you write your tests:
+        //
+        //Use ClassInitialize to run code before running the first test in the class
+        //[ClassInitialize()]
+        //public static void MyClassInitialize(TestContext testContext)
+        //{
+        //}
+        //
+        //Use ClassCleanup to run code after all tests in a class have run
+        //[ClassCleanup()]
+        //public static void MyClassCleanup()
+        //{
+        //}
+        //
+        //Use TestInitialize to run code before running each test
+        //[TestInitialize()]
+        //public void MyTestInitialize()
+        //{
+        //}
+        //
+        //Use TestCleanup to run code after each test has run
+        //[TestCleanup()]
+        //public void MyTestCleanup()
+        //{
+        //}
+        //
+        #endregion
+
+
+        /// <summary>
+        ///A test for IsValidColumn
+        ///</summary>
+        [TestMethod()]
+        public void IsValidColumnTest()
+        {
+            Assert.AreEqual(false, ExcelHelper.IsValidColumn(""));
+            Assert.AreEqual(false, ExcelHelper.IsValidColumn("1"));
+            Assert.AreEqual(false, ExcelHelper.IsValidColumn("A1"));
+            Assert.AreEqual(false, ExcelHelper.IsValidColumn("AA1"));
+            Assert.AreEqual(true, ExcelHelper.IsValidColumn("A"));
+            Assert.AreEqual(true, ExcelHelper.IsValidColumn("AA"));
+            Assert.AreEqual(true, ExcelHelper.IsValidColumn("AAA"));
+            Assert.AreEqual(true, ExcelHelper.IsValidColumn("Z"));
+            Assert.AreEqual(true, ExcelHelper.IsValidColumn("ZZ"));
+            Assert.AreEqual(true, ExcelHelper.IsValidColumn("XFD"));
+            Assert.AreEqual(false, ExcelHelper.IsValidColumn("ZAA"));
+            Assert.AreEqual(false, ExcelHelper.IsValidColumn("XZA"));
+            Assert.AreEqual(false, ExcelHelper.IsValidColumn("XFZ"));
+        }
+    }
+}
+