diff --git a/end_to_end_tests/golden-record/pyproject.toml b/end_to_end_tests/golden-record/pyproject.toml
index 04a8e5661..21177dd14 100644
--- a/end_to_end_tests/golden-record/pyproject.toml
+++ b/end_to_end_tests/golden-record/pyproject.toml
@@ -15,7 +15,7 @@ include = ["CHANGELOG.md", "my_test_api_client/py.typed"]
 [tool.poetry.dependencies]
 python = "^3.6"
 httpx = ">=0.15.4,<0.19.0"
-attrs = "^20.1.0"
+attrs = ">=20.1.0,<22.0.0"
 python-dateutil = "^2.8.0"
 
 [tool.black]
diff --git a/openapi_python_client/templates/pyproject.toml.jinja b/openapi_python_client/templates/pyproject.toml.jinja
index 3e63b17be..9e311a1a8 100644
--- a/openapi_python_client/templates/pyproject.toml.jinja
+++ b/openapi_python_client/templates/pyproject.toml.jinja
@@ -15,7 +15,7 @@ include = ["CHANGELOG.md", "{{ package_name }}/py.typed"]
 [tool.poetry.dependencies]
 python = "^3.6"
 httpx = ">=0.15.4,<0.19.0"
-attrs = "^20.1.0"
+attrs = ">=20.1.0,<22.0.0"
 python-dateutil = "^2.8.0"
 
 [tool.black]
diff --git a/openapi_python_client/templates/setup.py.jinja b/openapi_python_client/templates/setup.py.jinja
index 6f347cd1c..0dd31d23b 100644
--- a/openapi_python_client/templates/setup.py.jinja
+++ b/openapi_python_client/templates/setup.py.jinja
@@ -14,6 +14,6 @@ setup(
     package_dir={"": "{{ package_name }}"},
     packages=find_packages(where="{{ package_name }}"),
     python_requires=">=3.6, <4",
-    install_requires=["httpx >= 0.15.0, < 0.19.0", "attrs >= 20.1.0", "python-dateutil >= 2.8.0, < 3"],
+    install_requires=["httpx >= 0.15.0, < 0.19.0", "attrs >= 20.1.0, < 22.0.0", "python-dateutil >= 2.8.0, < 3"],
     package_data={"": ["CHANGELOG.md"], "{{ package_name }}": ["py.typed"]},
 )
diff --git a/poetry.lock b/poetry.lock
index 948be6c1f..7db8957b7 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -24,17 +24,17 @@ python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
 [[package]]
 name = "attrs"
-version = "20.3.0"
+version = "21.1.0"
 description = "Classes Without Boilerplate"
 category = "main"
 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", "furo", "sphinx", "pre-commit"]
-docs = ["furo", "sphinx", "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"]
+dev = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins", "zope.interface", "furo", "sphinx", "sphinx-notfound-page", "pre-commit"]
+docs = ["furo", "sphinx", "zope.interface", "sphinx-notfound-page"]
+tests = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins", "zope.interface"]
+tests_no_zope = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "mypy", "pytest-mypy-plugins"]
 
 [[package]]
 name = "autoflake"
@@ -670,7 +670,7 @@ testing = ["pytest (>=3.5,!=3.7.3)", "pytest-checkdocs (>=1.2.3)", "pytest-flake
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.6.2"
-content-hash = "afcb8ca9faf8cb0a4923dee5cbc303fbe35f326083f900d951ba21e9fcd344c0"
+content-hash = "b125cc4bc5456b335d0412e87dc21175738b4138a6eb9f4689b79d07171b8273"
 
 [metadata.files]
 appdirs = [
@@ -686,8 +686,8 @@ atomicwrites = [
     {file = "atomicwrites-1.4.0.tar.gz", hash = "sha256:ae70396ad1a434f9c7046fd2dd196fc04b12f9e91ffb859164193be8b6168a7a"},
 ]
 attrs = [
-    {file = "attrs-20.3.0-py2.py3-none-any.whl", hash = "sha256:31b2eced602aa8423c2aea9c76a724617ed67cf9513173fd3a4f03e3a929c7e6"},
-    {file = "attrs-20.3.0.tar.gz", hash = "sha256:832aa3cde19744e49938b91fea06d69ecb9e649c93ba974535d08ad92164f700"},
+    {file = "attrs-21.1.0-py2.py3-none-any.whl", hash = "sha256:8ee1e5f5a1afc5b19bdfae4fdf0c35ed324074bdce3500c939842c8f818645d9"},
+    {file = "attrs-21.1.0.tar.gz", hash = "sha256:3901be1cb7c2a780f14668691474d9252c070a756be0a9ead98cfeabfa11aeb8"},
 ]
 autoflake = [
     {file = "autoflake-1.4.tar.gz", hash = "sha256:61a353012cff6ab94ca062823d1fb2f692c4acda51c76ff83a8d77915fba51ea"},
diff --git a/pyproject.toml b/pyproject.toml
index 0eb6ad52b..d39350c1a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,7 +29,7 @@ isort = "^5.0.5"
 pyyaml = "^5.3.1"
 importlib_metadata = {version = "^2.0.0", python = "<3.8"}
 pydantic = "^1.6.1"
-attrs = "^20.1.0"
+attrs = "^21.0.0"
 python-dateutil = "^2.8.1"
 httpx = ">=0.15.4,<0.19.0"
 autoflake = "^1.4"