diff --git a/ClosedXML/ClosedXML/ClosedXML/XLHelper.cs b/ClosedXML/ClosedXML/ClosedXML/XLHelper.cs
index 1924814..e40da42 100644
--- a/ClosedXML/ClosedXML/ClosedXML/XLHelper.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/XLHelper.cs
@@ -172,7 +172,9 @@
 
         public static Boolean IsValidRangeAddress(IXLRangeAddress rangeAddress)
         {
-            return rangeAddress.FirstAddress.RowNumber >= 1 && rangeAddress.LastAddress.RowNumber <= MaxRowNumber
+
+            return !rangeAddress.IsInvalid 
+                   && rangeAddress.FirstAddress.RowNumber >= 1 && rangeAddress.LastAddress.RowNumber <= MaxRowNumber
                    && rangeAddress.FirstAddress.ColumnNumber >= 1 && rangeAddress.LastAddress.ColumnNumber <= MaxColumnNumber
                    && rangeAddress.FirstAddress.RowNumber <= rangeAddress.LastAddress.RowNumber
                    && rangeAddress.FirstAddress.ColumnNumber <= rangeAddress.LastAddress.ColumnNumber;