diff --git a/fedjax/core/client_samplers.py b/fedjax/core/client_samplers.py
index 2515367..8b61ad7 100644
--- a/fedjax/core/client_samplers.py
+++ b/fedjax/core/client_samplers.py
@@ -104,7 +104,7 @@ def sample(
     # Explicitly specify dtype as np.object to prevent numpy from stripping
     # trailing zero bytes from client ids that resulted in lookup KeyErrors.
     client_ids = random_state.choice(
-        np.array(self._client_ids, dtype=np.object),
+        np.array(self._client_ids, dtype=object),
         size=self._num_clients,
         replace=False)
     client_rngs = jax.random.split(
diff --git a/fedjax/core/serialization_test.py b/fedjax/core/serialization_test.py
index 4d93bfe..34c4b39 100644
--- a/fedjax/core/serialization_test.py
+++ b/fedjax/core/serialization_test.py
@@ -28,7 +28,7 @@ def test_dict(self):
         'float64':
             -np.arange(4, dtype=np.float64).reshape([1, 4]),
         'bytes':
-            np.array([b'a', b'bc', b'def'], dtype=np.object).reshape([3, 1]),
+            np.array([b'a', b'bc', b'def'], dtype=object).reshape([3, 1]),
     }
     output = serialization.msgpack_deserialize(
         serialization.msgpack_serialize(original))
@@ -37,7 +37,7 @@ def test_dict(self):
     npt.assert_array_equal(output['int32'], original['int32'])
     self.assertEqual(output['float64'].dtype, np.float64)
     npt.assert_array_equal(output['float64'], original['float64'])
-    self.assertEqual(output['bytes'].dtype, np.object)
+    self.assertEqual(output['bytes'].dtype, object)
     npt.assert_array_equal(output['bytes'], original['bytes'])
 
   def test_nested_list(self):
@@ -47,7 +47,7 @@ def test_nested_list(self):
             -np.arange(4, dtype=np.float64).reshape([1, 4]),
             [
                 np.array([b'a', b'bc', b'def'],
-                         dtype=np.object).reshape([3, 1]), []
+                         dtype=object).reshape([3, 1]), []
             ]
         ]
     ]
@@ -60,7 +60,7 @@ def test_nested_list(self):
     self.assertEqual(float64_array.dtype, np.float64)
     npt.assert_array_equal(float64_array, original[1][0])
     bytes_array, rest = rest
-    self.assertEqual(bytes_array.dtype, np.object)
+    self.assertEqual(bytes_array.dtype, object)
     npt.assert_array_equal(bytes_array, original[1][1][0])
     self.assertEqual(rest, [])
 
diff --git a/fedjax/datasets/scripts/sent140/data_to_sqlite.py b/fedjax/datasets/scripts/sent140/data_to_sqlite.py
index b28ac25..8285aac 100644
--- a/fedjax/datasets/scripts/sent140/data_to_sqlite.py
+++ b/fedjax/datasets/scripts/sent140/data_to_sqlite.py
@@ -113,13 +113,13 @@ def user_data_to_numpy(user_data: List[List[str]]) -> Dict[str, np.ndarray]:
     tweet_sentiment.append(bytes(y, 'utf-8'))
 
   np_data = {
-      'tweet_id': np.array(tweet_id, dtype=np.object),
-      'tweet_date': np.array(tweet_date, dtype=np.object),
-      'tweet_query': np.array(tweet_query, dtype=np.object),
-      'tweet_client': np.array(tweet_client, dtype=np.object),
-      'tweet_text': np.array(tweet_text, dtype=np.object),
-      'tweet_dataset': np.array(tweet_dataset, dtype=np.object),
-      'tweet_sentiment': np.array(tweet_sentiment, dtype=np.object)
+      'tweet_id': np.array(tweet_id, dtype=object),
+      'tweet_date': np.array(tweet_date, dtype=object),
+      'tweet_query': np.array(tweet_query, dtype=object),
+      'tweet_client': np.array(tweet_client, dtype=object),
+      'tweet_text': np.array(tweet_text, dtype=object),
+      'tweet_dataset': np.array(tweet_dataset, dtype=object),
+      'tweet_sentiment': np.array(tweet_sentiment, dtype=object)
   }
 
   return np_data
diff --git a/fedjax/datasets/shakespeare_test.py b/fedjax/datasets/shakespeare_test.py
index 9386f6c..e9069a6 100644
--- a/fedjax/datasets/shakespeare_test.py
+++ b/fedjax/datasets/shakespeare_test.py
@@ -26,7 +26,7 @@ class ShakespeareTest(absltest.TestCase):
 
   def test_preprocess_client(self):
     examples = shakespeare.preprocess_client(
-        None, {'snippets': np.array([b'hello', b'hi there'], dtype=np.object)},
+        None, {'snippets': np.array([b'hello', b'hi there'], dtype=object)},
         sequence_length=10)
     npt.assert_equal(
         examples, {
diff --git a/fedjax/datasets/stackoverflow_test.py b/fedjax/datasets/stackoverflow_test.py
index 4cf2625..8eef941 100644
--- a/fedjax/datasets/stackoverflow_test.py
+++ b/fedjax/datasets/stackoverflow_test.py
@@ -30,7 +30,7 @@ def test_preprocess_client(self):
             None, {
                 'tokens':
                     np.array([b'this is a test', b'may it not fail'],
-                             dtype=np.object),
+                             dtype=object),
                 'creation_date':
                     np.array([b'1970-01-01', b'2021-04-20']),
                 'type':
@@ -38,7 +38,7 @@ def test_preprocess_client(self):
             }), {
                 'tokens':
                     np.array([b'this is a test', b'may it not fail'],
-                             dtype=np.object),
+                             dtype=object),
                 'domain_id': [1, 0]
             })
 
@@ -49,7 +49,7 @@ def test_tokenizer(self):
     examples = {
         'tokens':
             np.array([b'three four five', b'five three four five six'],
-                     dtype=np.object)
+                     dtype=object)
     }
 
     with self.subTest('padding and truncation'):