diff --git a/pycbc/io/hdf.py b/pycbc/io/hdf.py
index 15911d545c9..e5d61afe4a1 100644
--- a/pycbc/io/hdf.py
+++ b/pycbc/io/hdf.py
@@ -49,7 +49,7 @@ def create_dataset(self, name, shape=None, dtype=None, data=None, **kwds):
         """
         Wrapper around h5py's create_dataset so that checksums are used
         """
-        if hasattr(data, 'dtype') and not data.dtype == object:
+        if isinstance(data, np.ndarray) and not data.dtype == object:
             kwds['fletcher32'] = True
         return h5py.Group.create_dataset(
             self,