diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index d10b71e9..f0a90a2a 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -2,6 +2,19 @@
 Changelog
 *********
 
+1.3.1 -- 2022-12-19
+===================
+
+Deprecation Announcement
+------------------------
+The AWS DynamoDB Encryption Client for Python Major Version 1 is End of Support.
+It will no longer receive security updates or bug fixes.
+Consider updating to the latest version of the AWS DynamoDB Encryption Client for Python.
+
+Maintenance
+------------------------
+* Emit Deprecation Warning on library initialization
+
 1.3.0 -- 2021-02-04
 ===================
 Adds the CachingMostRecentProvider and deprecates MostRecentProvider.
diff --git a/ci-requirements.txt b/ci-requirements.txt
index 053148f8..87aaac6e 100644
--- a/ci-requirements.txt
+++ b/ci-requirements.txt
@@ -1 +1 @@
-tox
+tox < 4.0
diff --git a/codebuild/python3.7.yml b/codebuild/python3.7.yml
index 1ac0daa6..dcb6b944 100644
--- a/codebuild/python3.7.yml
+++ b/codebuild/python3.7.yml
@@ -28,5 +28,5 @@ phases:
       # The choice of versions should be reviewed.
       - pyenv install 3.7.9
       - pyenv local 3.7.9
-      - pip install tox tox-pyenv
+      - pip install "tox < 4.0"
       - tox
diff --git a/codebuild/python3.8.yml b/codebuild/python3.8.yml
index cbac65cf..1609a046 100644
--- a/codebuild/python3.8.yml
+++ b/codebuild/python3.8.yml
@@ -16,5 +16,5 @@ phases:
     commands:
       - pyenv install 3.8.6
       - pyenv local 3.8.6
-      - pip install tox tox-pyenv
+      - pip install "tox < 4.0"
       - tox
diff --git a/src/dynamodb_encryption_sdk/__init__.py b/src/dynamodb_encryption_sdk/__init__.py
index 7b5dba80..b72f0052 100644
--- a/src/dynamodb_encryption_sdk/__init__.py
+++ b/src/dynamodb_encryption_sdk/__init__.py
@@ -11,6 +11,8 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 """DynamoDB Encryption Client."""
+import warnings
+
 from dynamodb_encryption_sdk.encrypted.client import EncryptedClient
 from dynamodb_encryption_sdk.encrypted.item import (
     decrypt_dynamodb_item,
@@ -32,3 +34,10 @@
     "EncryptedTable",
     "__version__",
 )
+
+warnings.warn(
+    "This major version (1.x) of the AWS DynamoDB Encryption Client for Python has reached End-of-Support.\n"
+    + "It will no longer receive security updates or bug fixes.\n"
+    + "Consider updating to the latest version of the AWS DynamoDB Encryption Client.",
+    DeprecationWarning,
+)
diff --git a/src/dynamodb_encryption_sdk/identifiers.py b/src/dynamodb_encryption_sdk/identifiers.py
index f4edd670..7c0c055b 100644
--- a/src/dynamodb_encryption_sdk/identifiers.py
+++ b/src/dynamodb_encryption_sdk/identifiers.py
@@ -14,7 +14,7 @@
 from enum import Enum
 
 __all__ = ("LOGGER_NAME", "CryptoAction", "EncryptionKeyType", "KeyEncodingType")
-__version__ = "1.3.0"
+__version__ = "1.3.1"
 
 LOGGER_NAME = "dynamodb_encryption_sdk"
 USER_AGENT_SUFFIX = "DynamodbEncryptionSdkPython/{}".format(__version__)
diff --git a/tox.ini b/tox.ini
index 557434ec..252dbaf2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -176,9 +176,9 @@ commands =
 [testenv:flake8]
 basepython = python3
 deps =
-    flake8
-    flake8-docstrings
-    flake8-isort
+    flake8==4.0.1
+    flake8-docstrings==1.6.0
+    flake8-isort==4.1.1
     # https://github.com/PyCQA/pydocstyle/issues/375
     pydocstyle<4.0.0
     # https://github.com/JBKahn/flake8-print/pull/30