diff --git a/ProcessLib/LocalAssemblerInterface.h b/ProcessLib/LocalAssemblerInterface.h
index d3f01175a99564d049d454468fb0913fb2714075..3b21962dfb3add86b290ced1a92547bc25d6b071 100644
--- a/ProcessLib/LocalAssemblerInterface.h
+++ b/ProcessLib/LocalAssemblerInterface.h
@@ -9,6 +9,8 @@
 
 #pragma once
 
+#include <Eigen/Dense>
+
 #include "NumLib/NumericsConfig.h"
 #include "MathLib/Point3d.h"