diff --git a/TIRAMISU/add_and_write_mechanism.py b/TIRAMISU/add_and_write_mechanism.py
index ce4f8175aaf70ad8909c15699bfa3b1ce4a7c151..a1e7adb8b3a097fab19ea064f3428a7fff2ae78a 100644
--- a/TIRAMISU/add_and_write_mechanism.py
+++ b/TIRAMISU/add_and_write_mechanism.py
@@ -496,6 +496,7 @@ def merging(outp, md_core, md_to_translate, max_len_name, model_core, model_to_t
             for species in to_add[1] :
                 if species[0] not in spe_list :
                     spe_list.append(species[0])
+                    trans=model2.trans[species[0]]
                     out.write(f'{trans.species:<20}{trans.geo:>10.0f}{trans.lj_p:>10.3f}{trans.lj_cd:>10.3f}{trans.dp:>10.3f}{trans.p:>10.3f}{trans.rr:>10.3f}\n'.upper())
         elif model2 !='' :
             out.write(f'{"!"*80}\n!!!!!{" "*70}!!!!!\n!!!!!{md2+" TRANSPORT":^70}!!!!!\n!!!!!{" "*70}!!!!!\n{"!"*80}\n'.upper())