diff --git a/Generators/GenInterfaces/GenInterfaces/IHiggsTruthCategoryTool.h b/Generators/GenInterfaces/GenInterfaces/IHiggsTruthCategoryTool.h
index 0c9b95d9c77bc5d35b52dc38f03699d4ec6342ca..c4ddab167f6898e691915db6018bb662ac9333a2 100644
--- a/Generators/GenInterfaces/GenInterfaces/IHiggsTruthCategoryTool.h
+++ b/Generators/GenInterfaces/GenInterfaces/IHiggsTruthCategoryTool.h
@@ -15,7 +15,7 @@
 #include "HepMC/GenEvent.h"
 
 namespace HTXS {
-  class HiggsClassification;
+  struct HiggsClassification;
 }
 
 class IHiggsTruthCategoryTool : public virtual asg::IAsgTool {
diff --git a/Reconstruction/TrackCaloClusterRec/TrackCaloClusterRecInterfaces/TrackCaloClusterRecInterfaces/ITrackCaloClusterTool.h b/Reconstruction/TrackCaloClusterRec/TrackCaloClusterRecInterfaces/TrackCaloClusterRecInterfaces/ITrackCaloClusterTool.h
index 801c5092ad6313431356addf8b4b453d2d8c3082..74fe200925bd018023f4423227c13d5ebb1673bc 100644
--- a/Reconstruction/TrackCaloClusterRec/TrackCaloClusterRecInterfaces/TrackCaloClusterRecInterfaces/ITrackCaloClusterTool.h
+++ b/Reconstruction/TrackCaloClusterRec/TrackCaloClusterRecInterfaces/TrackCaloClusterRecInterfaces/ITrackCaloClusterTool.h
@@ -16,7 +16,7 @@
 static const InterfaceID IID_ITrackCaloClusterTool("ITrackCaloClusterTool", 1, 0);
 
 
-class TrackCaloClusterInfo;
+struct TrackCaloClusterInfo;
 
 /** @brief Interface for tools creating particles using TCC methods and filling a FlowElementContainer */
 class ITrackCaloClusterTool : virtual public IAlgTool {