diff --git a/arc/species/zmat_test.py b/arc/species/zmat_test.py
index 86140ddeff..9f102fc9b5 100644
--- a/arc/species/zmat_test.py
+++ b/arc/species/zmat_test.py
@@ -1815,5 +1815,46 @@ def test_map_index_to_int(self):
         with self.assertRaises(TypeError):
             zmat.map_index_to_int('XY5486')
 
+    def test_add_atom_to_zmat_with_arbitrary_parameters(self):
+        """Test the add_atom_to_zmat_with_arbitrary_parameters() function."""
+        z = {'symbols': ('N', 'N', 'H', 'H'),
+                      'coords': ((None, None, None),
+                                 ('R_1_0', None, None),
+                                 ('R_2_1', 'A_2_1_0', None),
+                                 ('R_3_2', 'A_3_2_0', 'D_3_2_0_1')),
+                      'vars': {'R_1_0': 1.453439904003661, 'R_2_1': 1.0201432886642632, 'A_2_1_0': 121.26532344550412,
+                               'R_3_2': 1.7439821177668233, 'A_3_2_0': 66.26220791342335, 'D_3_2_0_1': 359.99999758516344},
+             'map': {0: 0, 1: 1, 2: 2, 3: 3}}
+        new_zmat = zmat.add_atom_to_zmat_with_arbitrary_parameters(z,
+                                                                   element='Cl',
+                                                                   r_index=2,
+                                                                   a_indices=(1, 2),
+                                                                   d_indices=(3, 0, 2),
+                                                                   r_value=1.5,
+                                                                   a_value=120.0,
+                                                                   d_value=180.0,
+                                                                   )
+        expected_zmat = {'coords': ((None, None, None),
+                                    ('R_1_0', None, None),
+                                    ('R_2_1', 'A_2_1_0', None),
+                                    ('R_3_2', 'A_3_2_0', 'D_3_2_0_1'),
+                                    ('R_4_3', 'A_4_3_2', 'D_4_3_2_1')),
+                         'map': {0: 0, 1: 1, 2: 4, 3: 2, 4: 3},
+                         'symbols': ('N', 'N', 'Cl', 'H', 'H'),
+                         'vars': {'A_2_1_0': 43.01291287044753,
+                                  'A_3_2_0': 116.8334890957394,
+                                  'A_4_3_2': 91.26532248920621,
+                                  'D_3_2_0_1': 0.002298234646018697,
+                                  'D_4_3_2_1': 359.9987217859366,
+                                  'R_1_0': 1.4534399860223848,
+                                  'R_2_1': 1.3268298846789657,
+                                  'R_3_2': 1.5000000794728576,
+                                  'R_4_3': 1.7439820494121707}}
+        self.assertEqual(new_zmat['symbols'], expected_zmat['symbols'])
+        self.assertEqual(new_zmat['vars'], expected_zmat['vars'])
+        self.assertEqual(new_zmat['coords'], expected_zmat['coords'])
+
+
+
 if __name__ == '__main__':
     unittest.main(testRunner=unittest.TextTestRunner(verbosity=2))