diff --git a/Shared/Core/Rule/GkvRules.cs b/Shared/Core/Rule/GkvRules.cs
index baaceb2dd..ba30309fa 100644
--- a/Shared/Core/Rule/GkvRules.cs
+++ b/Shared/Core/Rule/GkvRules.cs
@@ -91,7 +91,8 @@ namespace BS.Shared.Core.Rule
 
 		public static bool IsUnitDescriptionValid(IInvoiceItem invoiceItem)
 		{
-			if(invoiceItem == null) return false;
+			if(invoiceItem == null || invoiceItem.UnitDescription == null) 
+				return false;
 
 			// GPos. 123456
 			// 0123456