diff --git a/.gitignore b/.gitignore
index b35caad6..ab70786a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -116,3 +116,5 @@ pip-wheel-metadata/*
 tests/test_collections/*.nc
 .DS_Store
 dask-worker-space/
+
+CMIP6-MRI-ESM2-0*
diff --git a/intake_esm/cat.py b/intake_esm/cat.py
index 0eb5d873..c1fe2ff5 100644
--- a/intake_esm/cat.py
+++ b/intake_esm/cat.py
@@ -140,7 +140,7 @@ def save(
             The name of the file to save the catalog to.
         directory: str
             The directory or cloud storage bucket to save the catalog to.
-            If None, use the current directory
+            If None, use the current directory.
         catalog_type: str
             The type of catalog to save. Whether to save the catalog table as a dictionary
             in the JSON file or as a separate CSV file. Valid options are 'dict' and 'file'.
@@ -163,7 +163,13 @@ def save(
             raise ValueError(
                 f'catalog_type must be either "dict" or "file". Received catalog_type={catalog_type}'
             )
-        mapper = fsspec.get_mapper(f'{directory}' or '.', storage_options=storage_options)
+
+        # Check if the directory is None, and if it is, set it to the current directory
+        if directory is None:
+            directory = os.getcwd()
+
+        # Configure the fsspec mapper and associated filenames
+        mapper = fsspec.get_mapper(f'{directory}', storage_options=storage_options)
         fs = mapper.fs
         csv_file_name = f'{mapper.fs.protocol}://{mapper.root}/{name}.csv'
         json_file_name = f'{mapper.fs.protocol}://{mapper.root}/{name}.json'
diff --git a/tests/test_core.py b/tests/test_core.py
index 54c74ca8..90cd9459 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -1,4 +1,5 @@
 import ast
+import os
 
 import intake
 import pandas as pd
@@ -176,24 +177,29 @@ def test_catalog_keys_info():
 
 
 @pytest.mark.parametrize(
-    'catalog_type, to_csv_kwargs, json_dump_kwargs',
-    [('file', {'compression': 'bz2'}, {}), ('file', {'compression': 'gzip'}, {}), ('dict', {}, {})],
+    'catalog_type, to_csv_kwargs, json_dump_kwargs, directory',
+    [
+        ('file', {'compression': 'bz2'}, {}, '.'),
+        ('file', {'compression': 'gzip'}, {}, None),
+        ('dict', {}, {}, None),
+    ],
 )
-def test_catalog_serialize(tmp_path, catalog_type, to_csv_kwargs, json_dump_kwargs):
+def test_catalog_serialize(catalog_type, to_csv_kwargs, json_dump_kwargs, directory):
     cat = intake.open_esm_datastore(cdf_cat_sample_cmip6)
-    local_store = tmp_path
     cat_subset = cat.search(
         source_id='MRI-ESM2-0',
     )
     name = 'CMIP6-MRI-ESM2-0'
     cat_subset.serialize(
         name=name,
-        directory=str(local_store),
+        directory=directory,
         catalog_type=catalog_type,
         to_csv_kwargs=to_csv_kwargs,
         json_dump_kwargs=json_dump_kwargs,
     )
-    cat = intake.open_esm_datastore(f'{local_store}/{name}.json')
+    if directory is None:
+        directory = os.getcwd()
+    cat = intake.open_esm_datastore(f'{directory}/{name}.json')
     pd.testing.assert_frame_equal(
         cat_subset.df.reset_index(drop=True), cat.df.reset_index(drop=True)
     )