diff --git a/.coveragerc b/.coveragerc
index 01164f6..0287948 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -2,7 +2,8 @@
 omit =
 	# leading `*/` for pytest-dev/pytest-cov#456
 	*/.tox/*
-	*/pep517-build-env-*
+disable_warnings =
+	couldnt-parse
 
 [report]
 show_missing = True
diff --git a/pytest.ini b/pytest.ini
index aec763b..28e0d6f 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,8 +1,9 @@
 [pytest]
 norecursedirs=dist build .tox .eggs
 addopts=--doctest-modules --import-mode=importlib
-doctest_optionflags=ALLOW_UNICODE ELLIPSIS
 filterwarnings=
+	## upstream
+
 	# Ensure ResourceWarnings are emitted
 	default::ResourceWarning
 
@@ -18,3 +19,14 @@ filterwarnings=
 	ignore:<class 'pytest_flake8.Flake8Item'> is not using a cooperative constructor:pytest.PytestDeprecationWarning
 	ignore:The \(fspath. py.path.local\) argument to Flake8Item is deprecated.:pytest.PytestDeprecationWarning
 	ignore:Flake8Item is an Item subclass and should not be a collector:pytest.PytestWarning
+
+	# shopkeep/pytest-black#67
+	ignore:'encoding' argument not specified::pytest_black
+
+	# realpython/pytest-mypy#152
+	ignore:'encoding' argument not specified::pytest_mypy
+
+	# python/cpython#100750
+	ignore:'encoding' argument not specified::platform
+
+	## end upstream
diff --git a/tox.ini b/tox.ini
index ce5d994..9018256 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,10 +8,13 @@ toxworkdir={env:TOX_WORK_DIR:.tox}
 
 [testenv]
 deps =
+setenv =
+	PYTHONWARNDEFAULTENCODING = 1
 commands =
 	pytest {posargs}
 usedevelop = True
-extras = testing
+extras =
+	testing
 passenv =
 	GITHUB_ACTIONS