diff --git a/plugins/analyze_wf/analyze_wf.irp.f b/plugins/analyze_wf/analyze_wf.irp.f
index c37db55f..d8ede09a 100644
--- a/plugins/analyze_wf/analyze_wf.irp.f
+++ b/plugins/analyze_wf/analyze_wf.irp.f
@@ -3,6 +3,7 @@ program analyze_wf
   BEGIN_DOC
 ! Wave function analyzis
   END_DOC
+  PROVIDE mo_tot_num psi_det psi_coef
   read_wf = .True.
   SOFT_TOUCH read_wf
   call run()
@@ -29,11 +30,11 @@ subroutine run
   write(*,'(A)')  '============='
   write(*,'(A)')  ''
   do istate=1,N_states
-    call get_occupation_from_dets(occupation,istate)
     write(*,'(A)')  ''
     write(*,'(A,I3)'),  'State ', istate
     write(*,'(A)')  '---------------'
     write(*,'(A)')  ''
+    call get_occupation_from_dets(istate,occupation)
     write (*,'(A)')  '======== ================'
     class = 0
     do i=1,mo_tot_num
diff --git a/plugins/analyze_wf/occupation.irp.f b/plugins/analyze_wf/occupation.irp.f
index d426dc14..c208cda3 100644
--- a/plugins/analyze_wf/occupation.irp.f
+++ b/plugins/analyze_wf/occupation.irp.f
@@ -1,4 +1,4 @@
-subroutine get_occupation_from_dets(occupation, istate)
+subroutine get_occupation_from_dets(istate,occupation)
   implicit none
   double precision, intent(out)  :: occupation(mo_tot_num)
   integer, intent(in)            :: istate
@@ -9,6 +9,8 @@ subroutine get_occupation_from_dets(occupation, istate)
   integer                        :: list(N_int*bit_kind_size,2)
   integer                        :: n_elements(2)
   double precision               :: c
+  ASSERT (istate > 0) 
+  ASSERT (istate <= N_states) 
   
   occupation = 0.d0
   do i=1,N_det
@@ -16,6 +18,7 @@ subroutine get_occupation_from_dets(occupation, istate)
     call bitstring_to_list_ab(psi_det(1,1,i), list, n_elements, N_int)
     do ispin=1,2
       do j=1,n_elements(ispin)
+        ASSERT ( list(j,ispin) < mo_tot_num ) 
         occupation( list(j,ispin) ) += c
       enddo
     enddo