diff --git a/src/dagmc/DagMC.hpp b/src/dagmc/DagMC.hpp
index 2634ac6816..4c39a239ab 100644
--- a/src/dagmc/DagMC.hpp
+++ b/src/dagmc/DagMC.hpp
@@ -34,6 +34,7 @@ static const std::string GRAVEYARD_NAME = "mat:graveyard";
 
 class CartVect;
 class GeomQueryTool;
+class GeomQueryTool::RayHistory;
 
 /**\brief
  *