diff --git a/poetry.lock b/poetry.lock
index 61e1447..1a31d1f 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -15,7 +15,7 @@ optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
 [package.extras]
-dev = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface", "sphinx", "sphinx-rtd-theme", "pre-commit"]
+dev = ["coverage[toml] (>=5.0.2)", "hypothesis", "pre-commit", "pympler", "pytest (>=4.3.0)", "six", "sphinx", "sphinx-rtd-theme", "zope.interface"]
 docs = ["sphinx", "sphinx-rtd-theme", "zope.interface"]
 tests = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface"]
 tests_no_zope = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six"]
@@ -55,6 +55,9 @@ category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, <4"
 
+[package.dependencies]
+toml = {version = "*", optional = true, markers = "extra == \"toml\""}
+
 [package.extras]
 toml = ["toml"]
 
@@ -168,19 +171,18 @@ testing = ["argcomplete", "hypothesis (>=3.56)", "mock", "nose", "requests", "xm
 
 [[package]]
 name = "pytest-cov"
-version = "2.12.1"
+version = "4.0.0"
 description = "Pytest plugin for measuring coverage."
 category = "dev"
 optional = false
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
+python-versions = ">=3.6"
 
 [package.dependencies]
-coverage = ">=5.2.1"
+coverage = {version = ">=5.2.1", extras = ["toml"]}
 pytest = ">=4.6"
-toml = "*"
 
 [package.extras]
-testing = ["fields", "hunter", "process-tests", "six", "pytest-xdist", "virtualenv"]
+testing = ["fields", "hunter", "process-tests", "pytest-xdist", "six", "virtualenv"]
 
 [[package]]
 name = "pytest-mypy"
@@ -271,7 +273,7 @@ python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, <4"
 
 [package.extras]
 brotli = ["brotlipy (>=0.6.0)"]
-secure = ["pyOpenSSL (>=0.14)", "cryptography (>=1.3.4)", "idna (>=2.0.0)", "certifi", "ipaddress"]
+secure = ["certifi", "cryptography (>=1.3.4)", "idna (>=2.0.0)", "ipaddress", "pyOpenSSL (>=0.14)"]
 socks = ["PySocks (>=1.5.6,!=1.5.7,<2.0)"]
 
 [[package]]
@@ -285,7 +287,7 @@ python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.8"
-content-hash = "a9e780692115af4268bd9ded797053cb9e2fb3f356ec51378ee57f4eb6da8ef3"
+content-hash = "b198cbc09c6e4d89d530203daf07db2ed042814146828a027d6ac42e78ec7a05"
 
 [metadata.files]
 atomicwrites = [
@@ -397,8 +399,8 @@ pytest = [
     {file = "pytest-6.2.4.tar.gz", hash = "sha256:50bcad0a0b9c5a72c8e4e7c9855a3ad496ca6a881a3641b4260605450772c54b"},
 ]
 pytest-cov = [
-    {file = "pytest-cov-2.12.1.tar.gz", hash = "sha256:261ceeb8c227b726249b376b8526b600f38667ee314f910353fa318caa01f4d7"},
-    {file = "pytest_cov-2.12.1-py2.py3-none-any.whl", hash = "sha256:261bb9e47e65bd099c89c3edf92972865210c36813f80ede5277dceb77a4a62a"},
+    {file = "pytest-cov-4.0.0.tar.gz", hash = "sha256:996b79efde6433cdbd0088872dbc5fb3ed7fe1578b68cdbba634f14bb8dd0470"},
+    {file = "pytest_cov-4.0.0-py3-none-any.whl", hash = "sha256:2feb1b751d66a8bd934e5edfa2e961d11309dc37b73b0eabe73b5945fee20f6b"},
 ]
 pytest-mypy = [
     {file = "pytest-mypy-0.7.0.tar.gz", hash = "sha256:5a667d9a2b66bf98b3a494411f221923a6e2c3eafbe771104951aaec8985673d"},
diff --git a/pyproject.toml b/pyproject.toml
index ded37f9..d4f66e0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,7 +18,7 @@ xmltodict = "^0.12.0"
 [tool.poetry.dev-dependencies]
 requests-mock = "^1.9.3"
 pytest = "^6.2.4"
-pytest-cov = "^2.12.1"
+pytest-cov = "^4.0.0"
 pytest-mypy = "^0.7.0"
 
 [build-system]