diff --git a/CHANGELOG.md b/CHANGELOG.md
index e386ecd7..6943d5a6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## [1.4.1](https://github.com/googleapis/python-service-directory/compare/v1.4.0...v1.4.1) (2022-06-06)
+
+
+### Bug Fixes
+
+* **deps:** require protobuf <4.0.0dev ([#205](https://github.com/googleapis/python-service-directory/issues/205)) ([b693784](https://github.com/googleapis/python-service-directory/commit/b6937849043941bf5238e5101f2935a27660e872))
+
+
+### Documentation
+
+* fix changelog header to consistent size ([#206](https://github.com/googleapis/python-service-directory/issues/206)) ([73bd664](https://github.com/googleapis/python-service-directory/commit/73bd664112df42552cf125c35752001e0a395528))
+
 ## [1.4.0](https://github.com/googleapis/python-service-directory/compare/v1.3.1...v1.4.0) (2022-05-05)
 
 
@@ -17,7 +29,7 @@
 
 * fix type in docstring for map fields ([ab48a2a](https://github.com/googleapis/python-service-directory/commit/ab48a2a2f2dddfaf9bc18b53f99b379ad66098d2))
 
-### [1.3.1](https://github.com/googleapis/python-service-directory/compare/v1.3.0...v1.3.1) (2022-03-05)
+## [1.3.1](https://github.com/googleapis/python-service-directory/compare/v1.3.0...v1.3.1) (2022-03-05)
 
 
 ### Bug Fixes
@@ -37,7 +49,7 @@
 
 * resolve DuplicateCredentialArgs error when using credentials_file ([55c52b5](https://github.com/googleapis/python-service-directory/commit/55c52b5b67891ac723a34fae22040feb5b5fcf15))
 
-### [1.2.1](https://www.github.com/googleapis/python-service-directory/compare/v1.2.0...v1.2.1) (2021-11-01)
+## [1.2.1](https://www.github.com/googleapis/python-service-directory/compare/v1.2.0...v1.2.1) (2021-11-01)
 
 
 ### Bug Fixes
@@ -69,21 +81,21 @@
 
 * add context manager support in client ([#122](https://www.github.com/googleapis/python-service-directory/issues/122)) ([59229eb](https://www.github.com/googleapis/python-service-directory/commit/59229ebe9f17be35cb39119cbae2e19e7a4c8732))
 
-### [1.0.4](https://www.github.com/googleapis/python-service-directory/compare/v1.0.3...v1.0.4) (2021-09-30)
+## [1.0.4](https://www.github.com/googleapis/python-service-directory/compare/v1.0.3...v1.0.4) (2021-09-30)
 
 
 ### Bug Fixes
 
 * improper types in pagers generation ([1b0841d](https://www.github.com/googleapis/python-service-directory/commit/1b0841dec49d193c777601ff16ee0706395349b3))
 
-### [1.0.3](https://www.github.com/googleapis/python-service-directory/compare/v1.0.2...v1.0.3) (2021-09-24)
+## [1.0.3](https://www.github.com/googleapis/python-service-directory/compare/v1.0.2...v1.0.3) (2021-09-24)
 
 
 ### Bug Fixes
 
 * add 'dict' annotation type to 'request' ([b1982e1](https://www.github.com/googleapis/python-service-directory/commit/b1982e1e3d9214c93b59dbbb1f9ff00532fc6120))
 
-### [1.0.2](https://www.github.com/googleapis/python-service-directory/compare/v1.0.1...v1.0.2) (2021-07-28)
+## [1.0.2](https://www.github.com/googleapis/python-service-directory/compare/v1.0.1...v1.0.2) (2021-07-28)
 
 
 ### Bug Fixes
@@ -100,7 +112,7 @@
 
 * release as 1.0.2 ([#102](https://www.github.com/googleapis/python-service-directory/issues/102)) ([47caf13](https://www.github.com/googleapis/python-service-directory/commit/47caf1346029bc6d017a1498f3a9b97e396ef667))
 
-### [1.0.1](https://www.github.com/googleapis/python-service-directory/compare/v1.0.0...v1.0.1) (2021-07-20)
+## [1.0.1](https://www.github.com/googleapis/python-service-directory/compare/v1.0.0...v1.0.1) (2021-07-20)
 
 
 ### Bug Fixes
@@ -141,7 +153,7 @@
 
 * add `from_service_account_info` ([#45](https://www.github.com/googleapis/python-service-directory/issues/45)) ([db77e88](https://www.github.com/googleapis/python-service-directory/commit/db77e88a44ffdabd284d61775960079309071617))
 
-### [0.4.1](https://www.github.com/googleapis/python-service-directory/compare/v0.4.0...v0.4.1) (2021-02-11)
+## [0.4.1](https://www.github.com/googleapis/python-service-directory/compare/v0.4.0...v0.4.1) (2021-02-11)
 
 
 ### Bug Fixes
@@ -174,7 +186,7 @@
 
 * fix docs link ([#9](https://www.github.com/googleapis/python-service-directory/issues/9)) ([0f73da9](https://www.github.com/googleapis/python-service-directory/commit/0f73da9722e3e0c943b67063af4a7f9d0fc1f9e4))
 
-### [0.1.1](https://www.github.com/googleapis/python-service-directory/compare/v0.1.0...v0.1.1) (2020-04-17)
+## [0.1.1](https://www.github.com/googleapis/python-service-directory/compare/v0.1.0...v0.1.1) (2020-04-17)
 
 
 ### Bug Fixes
diff --git a/setup.py b/setup.py
index 22907e65..8c4f33d8 100644
--- a/setup.py
+++ b/setup.py
@@ -20,7 +20,7 @@
 
 import setuptools  # type: ignore
 
-version = "1.4.0"
+version = "1.4.1"
 
 package_root = os.path.abspath(os.path.dirname(__file__))
 
@@ -45,7 +45,8 @@
         # Until this issue is closed
         # https://github.com/googleapis/google-cloud-python/issues/10566
         "google-api-core >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
-        "proto-plus >= 1.15.0",
+        "proto-plus >= 1.15.0, <2.0.0dev",
+        "protobuf >= 3.19.0, <4.0.0dev",
         "grpc-google-iam-v1 >= 0.12.4, <1.0.0dev",
     ),
     python_requires=">=3.6",
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index ca8aeffc..60b7a7a5 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -8,3 +8,4 @@
 google-api-core==1.31.5
 proto-plus==1.15.0
 grpc-google-iam-v1==0.12.4
+protobuf==3.19.0
diff --git a/testing/constraints-3.7.txt b/testing/constraints-3.7.txt
index e69de29b..60b7a7a5 100644
--- a/testing/constraints-3.7.txt
+++ b/testing/constraints-3.7.txt
@@ -0,0 +1,11 @@
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List *all* library dependencies and extras in this file.
+# Pin the version to the lower bound.
+#
+# e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
+# Then this file should have foo==1.14.0
+google-api-core==1.31.5
+proto-plus==1.15.0
+grpc-google-iam-v1==0.12.4
+protobuf==3.19.0
diff --git a/tests/unit/gapic/servicedirectory_v1/test_lookup_service.py b/tests/unit/gapic/servicedirectory_v1/test_lookup_service.py
index 01da2bb2..4e21385b 100644
--- a/tests/unit/gapic/servicedirectory_v1/test_lookup_service.py
+++ b/tests/unit/gapic/servicedirectory_v1/test_lookup_service.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
@@ -25,7 +33,6 @@
 from google.oauth2 import service_account
 import grpc
 from grpc.experimental import aio
-import mock
 from proto.marshal.rules.dates import DurationRule, TimestampRule
 import pytest
 
diff --git a/tests/unit/gapic/servicedirectory_v1/test_registration_service.py b/tests/unit/gapic/servicedirectory_v1/test_registration_service.py
index 0c8fb917..218c0f67 100644
--- a/tests/unit/gapic/servicedirectory_v1/test_registration_service.py
+++ b/tests/unit/gapic/servicedirectory_v1/test_registration_service.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/tests/unit/gapic/servicedirectory_v1beta1/test_lookup_service.py b/tests/unit/gapic/servicedirectory_v1beta1/test_lookup_service.py
index 3f1744d1..0e976a12 100644
--- a/tests/unit/gapic/servicedirectory_v1beta1/test_lookup_service.py
+++ b/tests/unit/gapic/servicedirectory_v1beta1/test_lookup_service.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
@@ -25,7 +33,6 @@
 from google.oauth2 import service_account
 import grpc
 from grpc.experimental import aio
-import mock
 from proto.marshal.rules.dates import DurationRule, TimestampRule
 import pytest
 
diff --git a/tests/unit/gapic/servicedirectory_v1beta1/test_registration_service.py b/tests/unit/gapic/servicedirectory_v1beta1/test_registration_service.py
index cc3360bd..db6a8315 100644
--- a/tests/unit/gapic/servicedirectory_v1beta1/test_registration_service.py
+++ b/tests/unit/gapic/servicedirectory_v1beta1/test_registration_service.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
@@ -31,7 +39,6 @@
 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