diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/Cells/XLCell.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/Cells/XLCell.cs
index 8b83271..f5041b6 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/Cells/XLCell.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/Cells/XLCell.cs
@@ -1596,7 +1596,7 @@
                     if (style.NumberFormat.Format == String.Empty && style.NumberFormat.NumberFormatId == 0)
                         Style.NumberFormat.NumberFormatId = 46;
                 }
-                else if (Double.TryParse(val, out dTest))
+                else if (val.Trim() != "NaN" &&  Double.TryParse(val, out dTest))
                     _dataType = XLCellValues.Number;
                 else if (DateTime.TryParse(val, out dtTest) && dtTest >= BaseDate)
                 {
diff --git a/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/Cells/XLCellTest.cs b/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/Cells/XLCellTest.cs
index ec056f6..5451098 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/Cells/XLCellTest.cs
+++ b/ClosedXML/ClosedXML/ClosedXML_Tests/Excel/Cells/XLCellTest.cs
@@ -254,5 +254,25 @@
             var success = cell.TryGetValue(out outValue);
             Assert.IsFalse(success);
         }
+
+        [TestMethod]
+        public void NaN_is_not_a_number()
+        {
+            var ws = new XLWorkbook().Worksheets.Add("Sheet1");
+            var cell = ws.Cell("A1");
+            cell.Value = "NaN";
+
+            Assert.AreNotEqual(XLCellValues.Number ,cell.DataType);
+        }
+
+        [TestMethod]
+        public void Nan_is_not_a_number()
+        {
+            var ws = new XLWorkbook().Worksheets.Add("Sheet1");
+            var cell = ws.Cell("A1");
+            cell.Value = "Nan";
+
+            Assert.AreNotEqual(XLCellValues.Number, cell.DataType);
+        }
     }
 }
\ No newline at end of file