diff --git a/calour/experiment.py b/calour/experiment.py
index fc2c599e..bd743452 100644
--- a/calour/experiment.py
+++ b/calour/experiment.py
@@ -81,10 +81,14 @@ class Experiment:
     AmpliconExperiment
     '''
     def __init__(self, data, sample_metadata, feature_metadata=None,
-                 exp_metadata={}, description='', sparse=True):
+                 exp_metadata=None, description='', sparse=True):
         self.data = data
         self.sample_metadata = sample_metadata
+        if feature_metadata is None:
+            feature_metadata = pd.DataFrame(np.arange(data.shape[1]))
         self.feature_metadata = feature_metadata
+        if exp_metadata is None:
+            exp_metadata = {}
         self.exp_metadata = exp_metadata
         self.description = description
         self.normalized = 0