diff --git a/MathLib/LinAlg/MatrixVectorTraits.cpp b/MathLib/LinAlg/MatrixVectorTraits.cpp
index d1036ed4347d240bd323dd387d49741e5f10e2c3..dceca5ee11c47bc09b40634d18e577a643ac1238 100644
--- a/MathLib/LinAlg/MatrixVectorTraits.cpp
+++ b/MathLib/LinAlg/MatrixVectorTraits.cpp
@@ -8,6 +8,7 @@
  */
 
 #include "AssemblerLib/LocalToGlobalIndexMap.h"
+#include "MatrixProviderUser.h"
 #include "MatrixVectorTraits.h"
 
 #ifdef OGS_USE_EIGEN
diff --git a/MathLib/LinAlg/MatrixVectorTraits.h b/MathLib/LinAlg/MatrixVectorTraits.h
index 793e6c2bf823c2ba16c6f2e2c8fc257bd481759e..44f9f4892fa2335b4f005077bbc6ce344eb5978a 100644
--- a/MathLib/LinAlg/MatrixVectorTraits.h
+++ b/MathLib/LinAlg/MatrixVectorTraits.h
@@ -12,12 +12,12 @@
 
 #include<memory>
 
-#include "MatrixProviderUser.h"
-
 namespace MathLib
 {
 template<typename Matrix>
 struct MatrixVectorTraits;
+
+struct MatrixSpecifications;
 }
 
 #define SPECIALIZE_MATRIX_VECTOR_TRAITS(MATVEC, IDX) \