diff --git a/stix2/datastore/memory.py b/stix2/datastore/memory.py
index e833c57..bc7c385 100644
--- a/stix2/datastore/memory.py
+++ b/stix2/datastore/memory.py
@@ -211,16 +211,20 @@ class MemorySink(DataSink):
         else:
             bundle = v20.Bundle(all_objs, allow_custom=self.allow_custom)
 
-        if not os.path.exists(os.path.dirname(path)):
-            os.makedirs(os.path.dirname(path))
+        if path.endswith(".json"):
+            if not os.path.exists(os.path.dirname(path)):
+                os.makedirs(os.path.dirname(path))
+        else:
+            if not os.path.exists(path):
+                os.makedirs(path)
 
-        # if the user only provided a directory, use the bundle id for filename
-        if os.path.isdir(path):
+            # if the user only provided a directory, use the bundle id for filename
             path = os.path.join(path, bundle["id"] + ".json")
 
         with io.open(path, "w", encoding=encoding) as f:
             bundle = bundle.serialize(pretty=True, encoding=encoding, ensure_ascii=False)
             f.write(bundle)
+
         return path
     save_to_file.__doc__ = MemoryStore.save_to_file.__doc__
 
diff --git a/stix2/test/v20/test_datastore.py b/stix2/test/v20/test_datastore.py
index 606e5b0..f783d4c 100644
--- a/stix2/test/v20/test_datastore.py
+++ b/stix2/test/v20/test_datastore.py
@@ -4,7 +4,7 @@ from stix2.datastore import (
     CompositeDataSource, DataSink, DataSource, DataStoreMixin,
 )
 from stix2.datastore.filters import Filter
-from stix2.test.v20.constants import CAMPAIGN_MORE_KWARGS
+from .constants import CAMPAIGN_MORE_KWARGS
 
 
 def test_datasource_abstract_class_raises_error():
diff --git a/stix2/test/v20/test_datastore_filesystem.py b/stix2/test/v20/test_datastore_filesystem.py
index 47a4eec..906be52 100644
--- a/stix2/test/v20/test_datastore_filesystem.py
+++ b/stix2/test/v20/test_datastore_filesystem.py
@@ -5,7 +5,7 @@ import shutil
 import pytest
 
 import stix2
-from stix2.test.v20.constants import (
+from .constants import (
     CAMPAIGN_ID, CAMPAIGN_KWARGS, IDENTITY_ID, IDENTITY_KWARGS, INDICATOR_ID,
     INDICATOR_KWARGS, MALWARE_ID, MALWARE_KWARGS, RELATIONSHIP_IDS,
 )
diff --git a/stix2/test/v21/test_datastore.py b/stix2/test/v21/test_datastore.py
index 8a4bcdb..f783d4c 100644
--- a/stix2/test/v21/test_datastore.py
+++ b/stix2/test/v21/test_datastore.py
@@ -4,7 +4,7 @@ from stix2.datastore import (
     CompositeDataSource, DataSink, DataSource, DataStoreMixin,
 )
 from stix2.datastore.filters import Filter
-from stix2.test.v21.constants import CAMPAIGN_MORE_KWARGS
+from .constants import CAMPAIGN_MORE_KWARGS
 
 
 def test_datasource_abstract_class_raises_error():
diff --git a/stix2/test/v21/test_datastore_filesystem.py b/stix2/test/v21/test_datastore_filesystem.py
index 6954eb1..1af21b4 100644
--- a/stix2/test/v21/test_datastore_filesystem.py
+++ b/stix2/test/v21/test_datastore_filesystem.py
@@ -5,7 +5,7 @@ import shutil
 import pytest
 
 import stix2
-from stix2.test.v21.constants import (
+from .constants import (
     CAMPAIGN_ID, CAMPAIGN_KWARGS, IDENTITY_ID, IDENTITY_KWARGS, INDICATOR_ID,
     INDICATOR_KWARGS, MALWARE_ID, MALWARE_KWARGS, RELATIONSHIP_IDS,
 )