diff --git a/plugins/MRCC_Utils/mrcc_utils.irp.f b/plugins/MRCC_Utils/mrcc_utils.irp.f
index 8b72ed29..281b6760 100644
--- a/plugins/MRCC_Utils/mrcc_utils.irp.f
+++ b/plugins/MRCC_Utils/mrcc_utils.irp.f
@@ -684,6 +684,8 @@ END_PROVIDER
       do pp = hh_shortcut(hh), hh_shortcut(hh+1)-1
         if(is_active_exc(pp)) cycle
         lref = 0
+        AtB(pp) = 0.d0
+        X(pp) = 0.d0
         do II=1,N_det_ref
           call apply_hole_local(psi_ref(1,1,II), hh_exists(1, hh), myMask, ok, N_int)
           if(.not. ok) cycle
@@ -693,12 +695,12 @@ END_PROVIDER
           if(ind == -1) cycle
           ind = psi_non_ref_sorted_idx(ind)
           call get_phase(myDet(1,1), psi_ref(1,1,II), phase, N_int)
-          X(pp) += psi_ref_coef(II,s)**2
+          X(pp) = X(pp) + psi_ref_coef(II,s)*psi_ref_coef(II,s)
           AtB(pp) += psi_non_ref_coef(ind, s) * psi_ref_coef(II, s) * phase
           lref(II) = ind
-          if(phase < 0d0) lref(II) = -ind
+          if(phase < 0.d0) lref(II) = -ind
         end do
-        X(pp) =  AtB(pp) / X(pp)
+        X(pp) =  AtB(pp) 
         do II=1,N_det_ref
           if(lref(II) > 0) then
             rho_mrcc_init(lref(II)) = psi_ref_coef(II,s) * X(pp)
@@ -709,7 +711,7 @@ END_PROVIDER
       end do
     end do
     deallocate(lref)
-    
+
     x_new = x
     
     double precision               :: factor, resold
diff --git a/plugins/Psiref_Utils/psi_ref_utils.irp.f b/plugins/Psiref_Utils/psi_ref_utils.irp.f
index 41db2f10..c4147ebc 100644
--- a/plugins/Psiref_Utils/psi_ref_utils.irp.f
+++ b/plugins/Psiref_Utils/psi_ref_utils.irp.f
@@ -97,6 +97,10 @@ END_PROVIDER
    endif
  enddo
  N_det_non_ref = i_non_ref
+ if (N_det_non_ref < 1) then
+   print *,  'Error : All determinants are in the reference'
+   stop -1
+ endif
 END_PROVIDER
 
  BEGIN_PROVIDER [ integer(bit_kind), psi_non_ref_restart,  (N_int,2,psi_det_size) ]