diff --git a/src/Spring/Spring.Core/Spring.Core.2005.csproj b/src/Spring/Spring.Core/Spring.Core.2005.csproj
index e4fdd761..27f9f1c4 100644
--- a/src/Spring/Spring.Core/Spring.Core.2005.csproj
+++ b/src/Spring/Spring.Core/Spring.Core.2005.csproj
@@ -986,6 +986,7 @@
     <Compile Include="Util\ConfigXmlDocument.cs" />
     <Compile Include="Util\ConfigXmlElement.cs" />
     <Compile Include="Util\FatalReflectionException.cs" />
+    <Compile Include="Util\IoUtils.cs" />
     <Compile Include="Util\ITextPosition.cs" />
     <Compile Include="Util\ObjectUtils.cs" />
     <Compile Include="Util\ReflectionException.cs" />