diff --git a/HISTORY.rst b/HISTORY.rst
index b895f2e..d1e909a 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -3,9 +3,9 @@
 History
 -------
 
-v0.23 (unreleased)
-...................
-* improve documentation for contributing section, #441 @pilosus
+v0.23 (2019-04-04)
+..................
+* improve documentation for contributing section, #441 by @pilosus
 * improve README.rst to include essential information about the package, #446 by @pilosus
 * ``IntEnum`` support, #444 by @potykion
 * fix PyObject callable value, #409 by @pilosus
@@ -13,10 +13,10 @@ v0.23 (unreleased)
 * fix ``ForwardRef`` collection bug, #450 by @tigerwings
 * Support specialized ``ClassVars``, #455 by @tyrylu
 * fix JSON serialization for ``ipaddress`` types, #333 by @pilosus
-* add SecretStr and SecretBytes types, #452 by @atheuz
+* add ``SecretStr`` and ``SecretBytes`` types, #452 by @atheuz
 
 v0.22 (2019-03-29)
-....................
+..................
 * add ``IPv{4,6,Any}Network`` and ``IPv{4,6,Any}Interface`` types from ``ipaddress`` stdlib, #333 by @pilosus
 * add docs for ``datetime`` types, #386 by @pilosus
 * fix to schema generation in dataclass-based models, #408 by @pilosus
diff --git a/Makefile b/Makefile
index 0353e94..c08cc0b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,6 @@
 .DEFAULT_GOAL := all
+isort = isort -rc pydantic tests
+black = black -S -l 120 --target-version py36 pydantic tests
 
 .PHONY: install
 install:
@@ -8,15 +10,15 @@ install:
 
 .PHONY: format
 format:
-	isort -rc -w 120 pydantic tests
-	black -S -l 120 --target-version py36 pydantic tests
+	$(isort)
+	$(black)
 
 .PHONY: lint
 lint:
 	python setup.py check -rms
 	flake8 pydantic/ tests/
-	pytest pydantic -p no:sugar -q
-	black -S -l 120 --target-version py36 --check pydantic tests
+	$(isort) --check-only
+	$(black) --check
 
 .PHONY: mypy
 mypy:
diff --git a/pydantic/version.py b/pydantic/version.py
index ce6f618..91de422 100644
--- a/pydantic/version.py
+++ b/pydantic/version.py
@@ -2,4 +2,4 @@ from distutils.version import StrictVersion
 
 __all__ = ['VERSION']
 
-VERSION = StrictVersion('0.22')
+VERSION = StrictVersion('0.23')
diff --git a/setup.cfg b/setup.cfg
index c7869fd..78e988b 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,6 +1,5 @@
 [tool:pytest]
 testpaths = tests
-addopts = --isort
 timeout = 10
 filterwarnings = error
 
diff --git a/tests/requirements.txt b/tests/requirements.txt
index 48aff96..bcdad3f 100644
--- a/tests/requirements.txt
+++ b/tests/requirements.txt
@@ -8,6 +8,5 @@ pycodestyle==2.5.0
 pyflakes==2.1.1
 pytest==4.4.0
 pytest-cov==2.6.1
-pytest-isort==0.3.1
 pytest-mock==1.10.3
 pytest-sugar==0.9.2