diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9e465526..1d576a6d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@
 
 ### Enhancements
 
-* Changed default object_codec_class for ZarrIO to numcodecs.JSON. The issue with the old default (numcodecs.Pickle) was that it was not readable outside of Python. Also, exposed the object_codec_class as a parameter to the NWBZarrIO constructor.
+* Changed default object_codec_class for ZarrIO to numcodecs.JSON. The issue with the old default (numcodecs.Pickle) was that it was not readable outside of Python. Exposed the object_codec_class as a parameter to the NWBZarrIO constructor. Resort to Pickle for complex cases such as structured arrays or compound datasets with refs.
 
 ## 0.6.0 (February 21, 2024)
 
diff --git a/src/hdmf_zarr/backend.py b/src/hdmf_zarr/backend.py
index b31178d6..0fed1601 100644
--- a/src/hdmf_zarr/backend.py
+++ b/src/hdmf_zarr/backend.py
@@ -1052,7 +1052,7 @@ def write_dataset(self, **kwargs):  # noqa: C901
 
                 object_codec = self.__codec_cls()
                 if not isinstance(object_codec, numcodecs.Pickle):
-                    print(f'Resorting to Pickle codec for dataset {name} of {parent.name}')
+                    warnings.warn(f'Resorting to Pickle codec for dataset {name} of {parent.name}')
                     object_codec = numcodecs.Pickle()
 
                 # cast and store compound dataset
@@ -1287,7 +1287,7 @@ def __list_fill__(self, parent, name, data, options=None):  # noqa: C901
         if has_structured_array:
             object_codec = io_settings.get('object_codec')
             if not isinstance(object_codec, numcodecs.Pickle):
-                print(f'Warning: Resorting to Pickle codec for {name} of {parent.name}.')
+                warnings.warn(f'Resorting to Pickle codec for {name} of {parent.name}.')
                 io_settings['object_codec'] = numcodecs.Pickle()
 
         # Create the dataset