diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7ddeeb01..9f128914 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,13 @@
 
 [1]: https://pypi.org/project/google-cloud-iot/#history
 
+## [2.6.4](https://github.com/googleapis/python-iot/compare/v2.6.3...v2.6.4) (2022-10-07)
+
+
+### Bug Fixes
+
+* **deps:** Allow protobuf 3.19.5 ([#396](https://github.com/googleapis/python-iot/issues/396)) ([a31f61c](https://github.com/googleapis/python-iot/commit/a31f61c5a44ee872ac9c6f8a194ac384c92c7c34))
+
 ## [2.6.3](https://github.com/googleapis/python-iot/compare/v2.6.2...v2.6.3) (2022-10-03)
 
 
diff --git a/samples/api-client/accesstoken_example/requirements.txt b/samples/api-client/accesstoken_example/requirements.txt
index 82d3a1c1..e32727ea 100644
--- a/samples/api-client/accesstoken_example/requirements.txt
+++ b/samples/api-client/accesstoken_example/requirements.txt
@@ -1,9 +1,9 @@
 cryptography==38.0.1
 flaky==3.7.0
-google-api-python-client==2.63.0
+google-api-python-client==2.64.0
 google-auth-httplib2==0.1.0
 google-auth==2.12.0
-google-cloud-iot==2.6.2
+google-cloud-iot==2.6.3
 google-cloud-pubsub==2.13.7
 google-cloud-storage==2.5.0
 paho-mqtt==1.6.1
diff --git a/samples/api-client/manager/requirements.txt b/samples/api-client/manager/requirements.txt
index 6e9759e9..14ad08b0 100644
--- a/samples/api-client/manager/requirements.txt
+++ b/samples/api-client/manager/requirements.txt
@@ -1,9 +1,9 @@
 cryptography==38.0.1
 flaky==3.7.0
-google-api-python-client==2.63.0
+google-api-python-client==2.64.0
 google-auth-httplib2==0.1.0
 google-auth==2.12.0
-google-cloud-iot==2.6.2
+google-cloud-iot==2.6.3
 google-cloud-pubsub==2.13.7
 paho-mqtt==1.6.1
 pyjwt==2.5.0
diff --git a/setup.py b/setup.py
index da0e3897..269b0559 100644
--- a/setup.py
+++ b/setup.py
@@ -19,13 +19,13 @@
 
 name = "google-cloud-iot"
 description = "Cloud IoT API API client library"
-version = "2.6.3"
+version = "2.6.4"
 release_status = "Development Status :: 5 - Production/Stable"
 dependencies = [
     "google-api-core[grpc] >= 1.32.0, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.*,!=2.4.*,!=2.5.*,!=2.6.*,!=2.7.*",
     "grpc-google-iam-v1 >= 0.12.4, <1.0.0dev",
     "proto-plus >= 1.22.0, <2.0.0dev",
-    "protobuf >= 3.20.2, <5.0.0dev",
+    "protobuf>=3.19.5,<5.0.0dev,!=3.20.0,!=3.20.1,!=4.21.0,!=4.21.1,!=4.21.2,!=4.21.3,!=4.21.4,!=4.21.5",
 ]
 
 extras = {"libcst": "libcst >= 0.2.5"}
diff --git a/testing/constraints-3.7.txt b/testing/constraints-3.7.txt
index b9be78dc..d977db96 100644
--- a/testing/constraints-3.7.txt
+++ b/testing/constraints-3.7.txt
@@ -7,4 +7,4 @@
 google-api-core==1.32.0
 proto-plus==1.22.0
 grpc-google-iam-v1==0.12.4
-protobuf==3.20.2
+protobuf==3.19.5