diff --git a/packages/google-cloud-billing/tests/unit/gapic/billing_v1/test_cloud_billing.py b/packages/google-cloud-billing/tests/unit/gapic/billing_v1/test_cloud_billing.py
index 5c4559e66a86..ebc66801fcc2 100644
--- a/packages/google-cloud-billing/tests/unit/gapic/billing_v1/test_cloud_billing.py
+++ b/packages/google-cloud-billing/tests/unit/gapic/billing_v1/test_cloud_billing.py
@@ -13,9 +13,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-import math
 import os
 
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
+
+import math
+
 from google.api_core import gapic_v1, grpc_helpers, grpc_helpers_async, path_template
 from google.api_core import client_options
 from google.api_core import exceptions as core_exceptions
@@ -30,7 +38,6 @@
 from google.type import expr_pb2  # type: ignore
 import grpc
 from grpc.experimental import aio
-import mock
 from proto.marshal.rules.dates import DurationRule, TimestampRule
 import pytest
 
diff --git a/packages/google-cloud-billing/tests/unit/gapic/billing_v1/test_cloud_catalog.py b/packages/google-cloud-billing/tests/unit/gapic/billing_v1/test_cloud_catalog.py
index db8a4a83538d..f11d6986574a 100644
--- a/packages/google-cloud-billing/tests/unit/gapic/billing_v1/test_cloud_catalog.py
+++ b/packages/google-cloud-billing/tests/unit/gapic/billing_v1/test_cloud_catalog.py
@@ -13,9 +13,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-import math
 import os
 
+# try/except added for compatibility with python < 3.8
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock
+except ImportError:
+    import mock
+
+import math
+
 from google.api_core import gapic_v1, grpc_helpers, grpc_helpers_async, path_template
 from google.api_core import client_options
 from google.api_core import exceptions as core_exceptions
@@ -26,7 +34,6 @@
 from google.protobuf import timestamp_pb2  # type: ignore
 import grpc
 from grpc.experimental import aio
-import mock
 from proto.marshal.rules.dates import DurationRule, TimestampRule
 import pytest