diff --git a/CHANGELOG.md b/CHANGELOG.md
index e79f8ab..a46ae9e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,18 @@
 # Changelog
 
-### [1.0.1](https://github.com/googleapis/python-datastream/compare/v1.0.0...v1.0.1) (2022-05-06)
+## [1.0.2](https://github.com/googleapis/python-datastream/compare/v1.0.1...v1.0.2) (2022-06-03)
+
+
+### Bug Fixes
+
+* **deps:** require protobuf <4.0.0dev ([#100](https://github.com/googleapis/python-datastream/issues/100)) ([251b6b4](https://github.com/googleapis/python-datastream/commit/251b6b4bd215cd68b5aa72b529a15f0f94704471))
+
+
+### Documentation
+
+* fix changelog header to consistent size ([#101](https://github.com/googleapis/python-datastream/issues/101)) ([f3dc083](https://github.com/googleapis/python-datastream/commit/f3dc0837538cbd77869b49afb8b750314c068ddf))
+
+## [1.0.1](https://github.com/googleapis/python-datastream/compare/v1.0.0...v1.0.1) (2022-05-06)
 
 
 ### Documentation
@@ -14,14 +26,14 @@
 
 * bump release level to production/stable ([05b5c87](https://github.com/googleapis/python-datastream/commit/05b5c875df8b6be6d5e9c6a89ffca017e0b5a160))
 
-### [0.4.2](https://github.com/googleapis/python-datastream/compare/v0.4.1...v0.4.2) (2022-03-05)
+## [0.4.2](https://github.com/googleapis/python-datastream/compare/v0.4.1...v0.4.2) (2022-03-05)
 
 
 ### Bug Fixes
 
 * **deps:** require google-api-core>=1.31.5, >=2.3.2 ([#76](https://github.com/googleapis/python-datastream/issues/76)) ([f29eba0](https://github.com/googleapis/python-datastream/commit/f29eba05290746af2cb84463ad505eb427e36d98))
 
-### [0.4.1](https://github.com/googleapis/python-datastream/compare/v0.4.0...v0.4.1) (2022-02-26)
+## [0.4.1](https://github.com/googleapis/python-datastream/compare/v0.4.0...v0.4.1) (2022-02-26)
 
 
 ### Documentation
@@ -43,7 +55,7 @@
 * remove `GcsFileFormat` and `SchemaFileFormat` ([28dab85](https://github.com/googleapis/python-datastream/commit/28dab85bf3b4ad937760d5219623793936e39731))
 * remove `NoConnectivitySettings` ([28dab85](https://github.com/googleapis/python-datastream/commit/28dab85bf3b4ad937760d5219623793936e39731))
 
-### [0.3.1](https://www.github.com/googleapis/python-datastream/compare/v0.3.0...v0.3.1) (2021-11-01)
+## [0.3.1](https://www.github.com/googleapis/python-datastream/compare/v0.3.0...v0.3.1) (2021-11-01)
 
 
 ### Bug Fixes
@@ -76,14 +88,14 @@
 * add 'dict' annotation type to 'request' ([973c851](https://www.github.com/googleapis/python-datastream/commit/973c851b750768b8405c97d33ed4cfdd66d39d9a))
 * improper types in pagers generation ([09eaafd](https://www.github.com/googleapis/python-datastream/commit/09eaafd1b695b10bfc2bb212974eff11da76782c))
 
-### [0.1.3](https://www.github.com/googleapis/python-datastream/compare/v0.1.2...v0.1.3) (2021-08-30)
+## [0.1.3](https://www.github.com/googleapis/python-datastream/compare/v0.1.2...v0.1.3) (2021-08-30)
 
 
 ### Bug Fixes
 
 * **datastream:** Change a few resource pattern variables from camelCase to snake_case ([#20](https://www.github.com/googleapis/python-datastream/issues/20)) ([296962a](https://www.github.com/googleapis/python-datastream/commit/296962abf8d0b8cda4f3e1e978262c8628f4b31e))
 
-### [0.1.2](https://www.github.com/googleapis/python-datastream/compare/v0.1.1...v0.1.2) (2021-07-29)
+## [0.1.2](https://www.github.com/googleapis/python-datastream/compare/v0.1.1...v0.1.2) (2021-07-29)
 
 
 ### Bug Fixes
@@ -100,7 +112,7 @@
 
 * release as 0.1.2 ([#12](https://www.github.com/googleapis/python-datastream/issues/12)) ([15998c2](https://www.github.com/googleapis/python-datastream/commit/15998c223864ac8d6b2442f66ed42f19e1dc62ea))
 
-### [0.1.1](https://www.github.com/googleapis/python-datastream/compare/v0.1.0...v0.1.1) (2021-07-21)
+## [0.1.1](https://www.github.com/googleapis/python-datastream/compare/v0.1.0...v0.1.1) (2021-07-21)
 
 
 ### Bug Fixes
diff --git a/setup.py b/setup.py
index b369ee5..dae0264 100644
--- a/setup.py
+++ b/setup.py
@@ -21,7 +21,7 @@
 
 name = "google-cloud-datastream"
 description = "Datastream client library"
-version = "1.0.1"
+version = "1.0.2"
 release_status = "Development Status :: 5 - Production/Stable"
 url = "https://github.com/googleapis/python-datastream"
 dependencies = [
@@ -29,7 +29,8 @@
     # Until this issue is closed
     # https://github.com/googleapis/google-cloud-python/issues/10566
     "google-api-core[grpc] >= 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",
 ]
 
 package_root = os.path.abspath(os.path.dirname(__file__))
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index be5a64f..786e637 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -6,3 +6,4 @@
 # Then this file should have google-cloud-foo==1.14.0
 google-api-core==1.31.5
 proto-plus==1.15.0
+protobuf==3.19.0
diff --git a/testing/constraints-3.7.txt b/testing/constraints-3.7.txt
index e69de29..786e637 100644
--- a/testing/constraints-3.7.txt
+++ b/testing/constraints-3.7.txt
@@ -0,0 +1,9 @@
+# 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 "google-cloud-foo >= 1.14.0, < 2.0.0dev",
+# Then this file should have google-cloud-foo==1.14.0
+google-api-core==1.31.5
+proto-plus==1.15.0
+protobuf==3.19.0
diff --git a/tests/unit/gapic/datastream_v1/test_datastream.py b/tests/unit/gapic/datastream_v1/test_datastream.py
index 09e4ffb..8b91b0d 100644
--- a/tests/unit/gapic/datastream_v1/test_datastream.py
+++ b/tests/unit/gapic/datastream_v1/test_datastream.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 (
     future,
     gapic_v1,
@@ -38,7 +46,6 @@
 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
 
diff --git a/tests/unit/gapic/datastream_v1alpha1/test_datastream.py b/tests/unit/gapic/datastream_v1alpha1/test_datastream.py
index 4916f2b..0a7d5bb 100644
--- a/tests/unit/gapic/datastream_v1alpha1/test_datastream.py
+++ b/tests/unit/gapic/datastream_v1alpha1/test_datastream.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 (
     future,
     gapic_v1,
@@ -38,7 +46,6 @@
 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