diff --git a/dotnet/test/DotNetUnitTest/FileIO/DfrgFunctions.cs b/dotnet/test/DotNetUnitTest/FileIO/DfrgFunctions.cs
index e616a541e..839612c1e 100644
--- a/dotnet/test/DotNetUnitTest/FileIO/DfrgFunctions.cs
+++ b/dotnet/test/DotNetUnitTest/FileIO/DfrgFunctions.cs
@@ -1,3 +1,4 @@
+using System.IO;
 using GeneXus.Application;
 using GeneXus.Configuration;
 using Xunit;