diff --git a/orcasong/modules.py b/orcasong/modules.py
index d08696b226d2361ec89e35a3d98afecd1a9e5729..b486c0809e6b16de30c32ceeb5323aa2e0b8f919 100644
--- a/orcasong/modules.py
+++ b/orcasong/modules.py
@@ -39,7 +39,7 @@ class McInfoMaker(kp.Module):
                 else:
                     dtypes.append((key, np.float64))
         else:
-            dtypes = [(k, type(v)) for k, v in track.items()]
+            dtypes = None
         kp_hist = kp.dataclasses.Table(
             track, dtype=dtypes,  h5loc='y', name='event_info')
         if len(kp_hist) != 1: