diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index bd69053..8001c79 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -2,9 +2,9 @@
 
 Release history
 ---------------
-0.5.x (unreleased)
+0.5.1 (July 7th 2019)
 ++++++++++++++++++++++
-- ?
+- improved: pin pytest version to `version smaller than 5.0.0 <https://docs.pytest.org/en/latest/py27-py34-deprecation.html>`_
 
 0.5.0 (June 25th 2019)
 ++++++++++++++++++++++
diff --git a/dyndnsc/__init__.py b/dyndnsc/__init__.py
index 65e17d6..a4d3e9b 100644
--- a/dyndnsc/__init__.py
+++ b/dyndnsc/__init__.py
@@ -4,4 +4,4 @@
 
 from .core import getDynDnsClientForConfig, DynDnsClient  # noqa: @UnusedImport
 
-__version__ = "0.5.1dev0"
+__version__ = "0.5.1"
diff --git a/requirements-style.txt b/requirements-style.txt
index 732eb30..823f69b 100644
--- a/requirements-style.txt
+++ b/requirements-style.txt
@@ -1,5 +1,5 @@
 flake8>=3.7.5
-pydocstyle>=2.1.1
+pydocstyle>=2.1.1,<4.0.0
 flake8-bandit>=1.0.1
 flake8-bugbear>=17.12.0
 flake8-comprehensions>=1.4.1
diff --git a/setup.py b/setup.py
index 8e4a5dc..254f230 100644
--- a/setup.py
+++ b/setup.py
@@ -59,7 +59,7 @@
 TESTS_REQUIRE = [
     "mock; python_version < '3.0'",  # pep508 syntax may not work on older toolchains
     "bottle==0.12.13",
-    "pytest>=3.2.5"
+    "pytest>=3.2.5,<5.0.0"
 ]
 
 EXTRAS_REQUIRE = {}