diff --git a/efel/pyfeatures/pyfeatures.py b/efel/pyfeatures/pyfeatures.py
index 935e1f7c..ab140368 100644
--- a/efel/pyfeatures/pyfeatures.py
+++ b/efel/pyfeatures/pyfeatures.py
@@ -82,7 +82,9 @@ def impedance():
             else:
                 Z = fft_volt / fft_cur
                 norm_Z = abs(Z) / max(abs(Z))
-                select_idxs = numpy.swapaxes(numpy.argwhere((freq > 0) & (freq <= Z_max_freq)), 0, 1)[0]
+                select_idxs = numpy.swapaxes(
+                    numpy.argwhere((freq > 0) & (freq <= Z_max_freq)), 0, 1
+                )[0]
                 smooth_Z = gaussian_filter1d(norm_Z[select_idxs], 10)
                 ind_max = numpy.argmax(smooth_Z)
                 return freq[ind_max]
diff --git a/efel/units/units.json b/efel/units/units.json
index 538ef7a3..bbc8accc 100644
--- a/efel/units/units.json
+++ b/efel/units/units.json
@@ -143,5 +143,6 @@
     "initburst_sahp": "mV",
     "initburst_sahp_ssse": "mV",
     "initburst_sahp_vb": "mV",
-    "depol_block_bool": "constant"
+    "depol_block_bool": "constant",
+    "impedance": "Hz"
 }
diff --git a/tests/test_pyfeatures.py b/tests/test_pyfeatures.py
index 860f6ec9..df451837 100644
--- a/tests/test_pyfeatures.py
+++ b/tests/test_pyfeatures.py
@@ -383,6 +383,5 @@ def test_impedance():
 
     feature_name = "impedance"
 
-    expected_values = {feature_name: 4.23076923076923}
+    expected_values = {feature_name: 4.615384615384615}
     _test_expected_value(feature_name, expected_values)
-    assert False