diff --git a/ClosedXML/ClosedXML/ClosedXML_Net3.5/ClosedXML_Net3.5.csproj b/ClosedXML/ClosedXML/ClosedXML_Net3.5/ClosedXML_Net3.5.csproj
index d6e53d5..cc94e98 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Net3.5/ClosedXML_Net3.5.csproj
+++ b/ClosedXML/ClosedXML/ClosedXML_Net3.5/ClosedXML_Net3.5.csproj
@@ -192,6 +192,9 @@
     <Compile Include="..\ClosedXML\Excel\CalcEngine\Functions\XLMath.cs">
       <Link>Excel\CalcEngine\Functions\XLMath.cs</Link>
     </Compile>
+    <Compile Include="..\ClosedXML\Excel\CalcEngine\Functions\XLMatrix.cs">
+      <Link>Excel\CalcEngine\Functions\XLMatrix.cs</Link>
+    </Compile>
     <Compile Include="..\ClosedXML\Excel\CalcEngine\Token.cs">
       <Link>Excel\CalcEngine\Token.cs</Link>
     </Compile>