diff --git a/trainer.h b/trainer.h
index e1b57fb1f5bdbf1989532c679283027da4970053..c0b8582090353f12182afe1201b0e632e4ca482c 100644
--- a/trainer.h
+++ b/trainer.h
@@ -2,6 +2,7 @@
 #include "../CORE/config/config.h"
 #include "../MODELS/dc_selector.h"
 #include "descriptors_calc.h"
+#include "../MLIP/design_matrix/design_matrix.h"
 #include "design_matrix/functions/dm_function_base.h"
 #include "models/m_tadah_base.h"
 #include "nn_finder.h"