diff --git a/src/tc_bi_ortho/tc_utils.irp.f b/src/tc_bi_ortho/tc_utils.irp.f
index e0f29eb8..9023e2f0 100644
--- a/src/tc_bi_ortho/tc_utils.irp.f
+++ b/src/tc_bi_ortho/tc_utils.irp.f
@@ -45,8 +45,8 @@ subroutine write_tc_var()
 
     SIGMA_TC = 0.d0
     do j = 2, N_det
-      call htilde_mu_mat_bi_ortho(psi_det(1,1,1), psi_det(1,1,j), N_int, hmono, htwoe, hthree, htot_1j)
-      call htilde_mu_mat_bi_ortho(psi_det(1,1,j), psi_det(1,1,1), N_int, hmono, htwoe, hthree, htot_j1)
+      call htilde_mu_mat_bi_ortho_slow(psi_det(1,1,1), psi_det(1,1,j), N_int, hmono, htwoe, hthree, htot_1j)
+      call htilde_mu_mat_bi_ortho_slow(psi_det(1,1,j), psi_det(1,1,1), N_int, hmono, htwoe, hthree, htot_j1)
       SIGMA_TC = SIGMA_TC + htot_1j * htot_j1
     enddo