diff --git a/src/hdmf_zarr/nwb.py b/src/hdmf_zarr/nwb.py
index 275a1164..582f1a63 100644
--- a/src/hdmf_zarr/nwb.py
+++ b/src/hdmf_zarr/nwb.py
@@ -30,6 +30,11 @@ def __init__(self, **kwargs):
             path, mode, manager, extensions, load_namespaces, synchronizer, storage_options = \
                 popargs('path', 'mode', 'manager', 'extensions',
                         'load_namespaces', 'synchronizer', 'storage_options', kwargs)
+
+            io_modes_that_create_file = ['w', 'w-', 'x']
+            if mode in io_modes_that_create_file or manager is not None or extensions is not None:
+                load_namespaces = False
+
             if load_namespaces:
                 tm = get_type_map()
                 super(NWBZarrIO, self).load_namespaces(tm, path, storage_options)