diff --git a/CHANGELOG.md b/CHANGELOG.md
index 546e996..5423983 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog
 
+## Unreleased
+* Fix missing deprecation warnings import causing payment method creation and updates with legacy fields to raise `NameError`
+
 ## 4.48.0
 * Add `Transaction.reverse()` to automatically void or fully refund a transaction
 * Add `previous_mastercard_transaction_link_id` to `external_vault` on `Transaction` and `CreditCardVerification.create`
diff --git a/braintree/payment_method_gateway.py b/braintree/payment_method_gateway.py
index 66094e1..8d09811 100644
--- a/braintree/payment_method_gateway.py
+++ b/braintree/payment_method_gateway.py
@@ -27,6 +27,7 @@
 from braintree.util.validation import is_invalid_path_segment
 
 import sys
+import warnings
 from urllib.parse import urlencode
 
 
diff --git a/tests/unit/test_payment_method_gateway.py b/tests/unit/test_payment_method_gateway.py
index 445a70b..205848c 100644
--- a/tests/unit/test_payment_method_gateway.py
+++ b/tests/unit/test_payment_method_gateway.py
@@ -214,3 +214,35 @@ def setup_payment_method_gateway_and_mock_http(self):
         http_mock = MagicMock(name='config.http.delete')
         braintree_gateway.config.http = http_mock
         return payment_method_gateway, http_mock
+
+
+class TestPaymentMethodGatewayDeprecation(unittest.TestCase):
+    def test_create_with_deprecated_device_session_id(self):
+        gateway = PaymentMethodGateway(BraintreeGateway(Configuration.instantiate()))
+        gateway._post = MagicMock()
+        params = {"device_session_id": "legacy-session"}
+
+        with self.assertWarnsRegex(DeprecationWarning, "device_session_id is deprecated"):
+            result = gateway.create(params)
+
+        gateway._post.assert_called_once_with("/payment_methods", {"payment_method": params})
+        self.assertIs(result, gateway._post.return_value)
+
+    def test_update_with_deprecated_attributes(self):
+        cases = [
+            ("device_session_id", "device_session_id is deprecated"),
+            ("fraud_merchant_id", "fraud_merchant_id is deprecated"),
+            ("venmo_sdk_payment_method_code", "The Venmo SDK integration is Unsupported"),
+        ]
+        for attribute, message in cases:
+            with self.subTest(attribute=attribute):
+                gateway = PaymentMethodGateway(BraintreeGateway(Configuration.instantiate()))
+                gateway._put = MagicMock()
+                params = {attribute: "legacy-value"}
+
+                with self.assertWarnsRegex(DeprecationWarning, message):
+                    result = gateway.update("some_token", params)
+
+                gateway._put.assert_called_once_with(
+                    "/payment_methods/any/some_token", {"payment_method": params})
+                self.assertIs(result, gateway._put.return_value)