diff --git a/ipfx/dataset/ephys_data_set.py b/ipfx/dataset/ephys_data_set.py
index e90900ff..f56ecc77 100644
--- a/ipfx/dataset/ephys_data_set.py
+++ b/ipfx/dataset/ephys_data_set.py
@@ -228,6 +228,10 @@ def sweep(self, sweep_number: int) -> Sweep:
 
         sweep_data = self.get_sweep_data(sweep_number)
         sweep_metadata = self._data.get_sweep_metadata(sweep_number)
+        if "autobias_v" in sweep_metadata.keys():
+            autobias_v = sweep_metadata["autobias_v"]
+        else:
+            autobias_v = None
 
         time = np.arange(
             len(sweep_data["stimulus"])
@@ -248,8 +252,8 @@ def sweep(self, sweep_number: int) -> Sweep:
                 sampling_rate=sweep_data["sampling_rate"],
                 sweep_number=sweep_number,
                 clamp_mode=sweep_metadata["clamp_mode"],
-                autobias_v = sweep_metadata["autobias_v"],
                 epochs=sweep_data.get("epochs", None),
+                autobias_v = autobias_v
             )
 
         except Exception:
diff --git a/tests/dataset/test_mies_nwb_data.py b/tests/dataset/test_mies_nwb_data.py
index c76fc949..641bff47 100644
--- a/tests/dataset/test_mies_nwb_data.py
+++ b/tests/dataset/test_mies_nwb_data.py
@@ -58,6 +58,7 @@ def test_get_sweep_metadata(mies_nwb_data):
         'stimulus_code_ext': 'STIMULUS_CODE[1]',
         'clamp_mode': 'CurrentClamp',
         'stimulus_name': 'expected name',
+        'autobias_v': None
     }
 
     obtained = mies_nwb_data.get_sweep_metadata(sweep_number=4)