diff --git a/Grid/qcd/action/ActionCore.h b/Grid/qcd/action/ActionCore.h
index 6544318d..2ec74a95 100644
--- a/Grid/qcd/action/ActionCore.h
+++ b/Grid/qcd/action/ActionCore.h
@@ -58,6 +58,8 @@ NAMESPACE_CHECK(Scalar);
 ////////////////////////////////////////////
 // Utility functions
 ////////////////////////////////////////////
+#include <Grid/qcd/action/momentum/MomentumFilter.h>
+//#include <Grid/qcd/action/momentum/DDHMCfilter.h>
 #include <Grid/qcd/utils/Metric.h>
 NAMESPACE_CHECK(Metric);
 #include <Grid/qcd/utils/CovariantLaplacian.h>