diff --git a/Reconstruction/VKalVrt/GNNVertexConstructor/GNNVertexConstructor/GNNVertexConstructorTool.h b/Reconstruction/VKalVrt/GNNVertexConstructor/GNNVertexConstructor/GNNVertexConstructorTool.h
index 02430380a01da32dfeca86fb82e57835c60c1d9f..a34e2cabc9a0d19b737676e1e6efc0f13b9c06f6 100644
--- a/Reconstruction/VKalVrt/GNNVertexConstructor/GNNVertexConstructor/GNNVertexConstructorTool.h
+++ b/Reconstruction/VKalVrt/GNNVertexConstructor/GNNVertexConstructor/GNNVertexConstructorTool.h
@@ -90,6 +90,7 @@ namespace Trk {
 class TrkVKalVrtFitter;
 class IVertexFitter;
 class IVKalState;
+class VxSecVKalVertexInfo;
 } // namespace Trk
 
 namespace Rec {