diff --git a/base/modules/psb_const_mod.F90 b/base/modules/psb_const_mod.F90
index 4809fc01..ffdccd62 100644
--- a/base/modules/psb_const_mod.F90
+++ b/base/modules/psb_const_mod.F90
@@ -216,6 +216,7 @@ module psb_const_mod
   integer(psb_ipk_), parameter, public :: psb_err_no_optional_arg_=581
   integer(psb_ipk_), parameter, public :: psb_err_arg_m_required_=582
   integer(psb_ipk_), parameter, public :: psb_err_many_optional_arg_=583
+  integer(psb_ipk_), parameter, public :: psb_err_optional_arg_pair_=584
   integer(psb_ipk_), parameter, public :: psb_err_spmat_invalid_state_=600
   integer(psb_ipk_), parameter, public :: psb_err_missing_override_method_=700
   integer(psb_ipk_), parameter, public :: psb_err_invalid_dynamic_type_=701
diff --git a/base/modules/psb_error_mod.F90 b/base/modules/psb_error_mod.F90
index 0ea6f70c..5d249412 100644
--- a/base/modules/psb_error_mod.F90
+++ b/base/modules/psb_error_mod.F90
@@ -744,6 +744,13 @@ contains
            &'("One of the optional arguments  ",a," must be present")')&
            & trim(a_e_d)
 
+    case(psb_err_optional_arg_pair_)
+      allocate(achmsg(2)) 
+      achmsg(1) = tmpmsg
+      write(achmsg(2),&
+           &'("The optional arguments  ",a," must be present together")')&
+           & trim(a_e_d)
+
     case(psb_err_arg_m_required_)
       allocate(achmsg(2)) 
       achmsg(1) = tmpmsg