diff --git a/src/ZSOLVER/zconjgrad.f90 b/src/MNH/zconjgrad.f90
similarity index 97%
rename from src/ZSOLVER/zconjgrad.f90
rename to src/MNH/zconjgrad.f90
index 594376e4776cd200495c4a380b13d3c99b81aaa7..ed927d553c471b034f9f631c5ecb89534f899be6 100644
--- a/src/ZSOLVER/zconjgrad.f90
+++ b/src/MNH/zconjgrad.f90
@@ -1,13 +1,9 @@
-!MNH_LIC Copyright 1994-2014 CNRS, Meteo-France and Universite Paul Sabatier
+!MNH_LIC Copyright 1994-2023 CNRS, Meteo-France and Universite Paul Sabatier
 !MNH_LIC This is part of the Meso-NH software governed by the CeCILL-C licence
 !MNH_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt  
 !MNH_LIC for details. version 1.
 !-----------------------------------------------------------------
-!--------------- special set of characters for RCS information
-!-----------------------------------------------------------------
-! $Source$ $Revision$
-! MASDEV4_7 solver 2006/05/18 13:07:25
-!-----------------------------------------------------------------
+#ifdef MNH_MGSOLVER
 !     ####################
       MODULE MODI_ZCONJGRAD
 !     ####################
@@ -290,3 +286,4 @@ PPHI = PPHI + ZLAMBDA * ZP
 !-------------------------------------------------------------------------------
 !
 END SUBROUTINE ZCONJGRAD
+#endif
diff --git a/src/ZSOLVER/zsolver.f90 b/src/MNH/zsolver.f90
similarity index 99%
rename from src/ZSOLVER/zsolver.f90
rename to src/MNH/zsolver.f90
index 426a5e0c96a9bb64a6e0117ee49c247d285f88ce..2c618266e0fe1f016a886da6591295daf1753e04 100644
--- a/src/ZSOLVER/zsolver.f90
+++ b/src/MNH/zsolver.f90
@@ -1,8 +1,9 @@
-!MNH_LIC Copyright 1994-2022 CNRS, Meteo-France and Universite Paul Sabatier
+!MNH_LIC Copyright 1994-2023 CNRS, Meteo-France and Universite Paul Sabatier
 !MNH_LIC This is part of the Meso-NH software governed by the CeCILL-C licence
 !MNH_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt  
 !MNH_LIC for details. version 1.
 !-----------------------------------------------------------------
+#ifdef MNH_MGSOLVER
 !     ####################
       MODULE MODI_ZSOLVER
 !     ####################
@@ -362,3 +363,4 @@ CALL MNH_MEM_RELEASE()
 !-------------------------------------------------------------------------------
 !
 END SUBROUTINE ZSOLVER
+#endif
diff --git a/src/ZSOLVER/zsolver_inv.f90 b/src/MNH/zsolver_inv.f90
similarity index 99%
rename from src/ZSOLVER/zsolver_inv.f90
rename to src/MNH/zsolver_inv.f90
index c2e4b127fccef4e443c749023a3c22ffa2fd194a..078e1d2261445750718f1cc1db67b2b95400a137 100644
--- a/src/ZSOLVER/zsolver_inv.f90
+++ b/src/MNH/zsolver_inv.f90
@@ -1,8 +1,9 @@
-!MNH_LIC Copyright 1994-2022 CNRS, Meteo-France and Universite Paul Sabatier
+!MNH_LIC Copyright 1994-2023 CNRS, Meteo-France and Universite Paul Sabatier
 !MNH_LIC This is part of the Meso-NH software governed by the CeCILL-C licence
 !MNH_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt  
 !MNH_LIC for details. version 1.
 !-----------------------------------------------------------------
+#ifdef MNH_MGSOLVER
 !     ####################
       MODULE MODI_ZSOLVER_INV
 !     ####################
@@ -521,3 +522,4 @@ INTEGER :: ZDXM2, ZDYM2
 END SUBROUTINE PF_1_Y_BOUND
   !------------------------------------------------------------------------------  
 END SUBROUTINE ZSOLVER_INV
+#endif