diff --git a/pyscf/tools/trexio.py b/pyscf/tools/trexio.py
index 73eaa1d70..ca1fef8d3 100644
--- a/pyscf/tools/trexio.py
+++ b/pyscf/tools/trexio.py
@@ -460,8 +460,6 @@ def get_occsa_and_occsb(mcscf, norb, nelec, ci_threshold=0.):
     return occsa_sorted, occsb_sorted, ci_values_sorted, num_determinants
 
 def det_to_trexio(mcscf, norb, nelec, trexio_file, ci_threshold=0., chunk_size=100000):
-    from trexio_tools.group_tools import determinant as trexio_det
-
     ncore = mcscf.ncore
     int64_num = trexio.get_int64_num(trexio_file)
 
@@ -472,8 +470,8 @@ def det_to_trexio(mcscf, norb, nelec, trexio_file, ci_threshold=0., chunk_size=1
         occsa_upshifted = [orb for orb in range(ncore)] + [orb+ncore for orb in a]
         occsb_upshifted = [orb for orb in range(ncore)] + [orb+ncore for orb in b]
         det_tmp = []
-        det_tmp += trexio_det.to_determinant_list(occsa_upshifted, int64_num)
-        det_tmp += trexio_det.to_determinant_list(occsb_upshifted, int64_num)
+        det_tmp += trexio.to_bitfield_list(int64_num, occsa_upshifted)
+        det_tmp += trexio.to_bitfield_list(int64_num, occsb_upshifted)
         det_list.append(det_tmp)
 
     if num_determinants > chunk_size: