diff --git a/src/MNH/prep_ideal_case.f90 b/src/MNH/prep_ideal_case.f90
index 5bb6611a26ee3eb4f1be4843ca11492b5342a4ad..6f30ae294b86920fa6fa2e83f8d25f8ad28183ee 100644
--- a/src/MNH/prep_ideal_case.f90
+++ b/src/MNH/prep_ideal_case.f90
@@ -377,6 +377,9 @@ USE MODE_IO_FIELD_WRITE,   only: IO_Field_write, IO_Header_write
 USE MODE_IO_FILE,          only: IO_File_close, IO_File_open
 USE MODE_IO_MANAGE_STRUCT, only: IO_File_add2list
 USE MODE_ll
+#ifdef MNH_OPENACC
+USE MODE_MNH_ZWORK,        only: MNH_ALLOC_ZWORK
+#endif
 USE MODE_MODELN_HANDLER
 use mode_field,            only: Alloc_field_scalars, Ini_field_list, Ini_field_scalars
 USE MODE_MSG
@@ -1195,6 +1198,10 @@ ELSE                                   ! 3D case
     ALLOCATE(XLBYSVM(0,0,0,0))
   END IF
 END IF
+#ifdef MNH_OPENACC
+
+CALL MNH_ALLOC_ZWORK( 1 )
+#endif
 !
 !
 !-------------------------------------------------------------------------------