diff --git a/poetry.lock b/poetry.lock
index e78628c..5e3b570 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -26,38 +26,26 @@ optional = false
 python-versions = ">=3.5.3"
 version = "3.0.1"
 
-[[package]]
-category = "main"
-description = "Classes Without Boilerplate"
-name = "attrs"
-optional = false
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "19.3.0"
-
-[package.extras]
-azure-pipelines = ["coverage", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface", "pytest-azurepipelines"]
-dev = ["coverage", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface", "sphinx", "pre-commit"]
-docs = ["sphinx", "zope.interface"]
-tests = ["coverage", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface"]
-
 [[package]]
 category = "main"
 description = "The uncompromising code formatter."
 name = "black"
 optional = false
 python-versions = ">=3.6"
-version = "19.10b0"
+version = "20.8b1"
 
 [package.dependencies]
 appdirs = "*"
-attrs = ">=18.1.0"
-click = ">=6.5"
+click = ">=7.1.2"
+mypy-extensions = ">=0.4.3"
 pathspec = ">=0.6,<1"
-regex = "*"
-toml = ">=0.9.4"
+regex = ">=2020.1.8"
+toml = ">=0.10.1"
 typed-ast = ">=1.4.0"
+typing-extensions = ">=3.7.4"
 
 [package.extras]
+colorama = ["colorama (>=0.4.3)"]
 d = ["aiohttp (>=3.3.2)", "aiohttp-cors"]
 
 [[package]]
@@ -74,7 +62,7 @@ description = "Composable command line interface toolkit"
 name = "click"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
-version = "7.1.1"
+version = "7.1.2"
 
 [[package]]
 category = "dev"
@@ -208,6 +196,14 @@ optional = false
 python-versions = "*"
 version = "0.6.1"
 
+[[package]]
+category = "main"
+description = "Experimental type system extensions for programs checked with the mypy typechecker."
+name = "mypy-extensions"
+optional = false
+python-versions = "*"
+version = "0.4.3"
+
 [[package]]
 category = "dev"
 description = "Node.js virtual environment builder"
@@ -389,7 +385,7 @@ version = "0.15.0"
 h11 = ">=0.8.1"
 
 [metadata]
-content-hash = "3deb7796dc17ba376bd32d2f116f7fbb0772374c3a9a33397a4ac1be747c5e5c"
+content-hash = "8ac09e5a0a140e676d558c9babd1f9ab85995508139e61c68b046fab9e9e2a26"
 python-versions = "^3.8"
 
 [metadata.files]
@@ -405,21 +401,17 @@ async-timeout = [
     {file = "async-timeout-3.0.1.tar.gz", hash = "sha256:0c3c816a028d47f659d6ff5c745cb2acf1f966da1fe5c19c77a70282b25f4c5f"},
     {file = "async_timeout-3.0.1-py3-none-any.whl", hash = "sha256:4291ca197d287d274d0b6cb5d6f8f8f82d434ed288f962539ff18cc9012f9ea3"},
 ]
-attrs = [
-    {file = "attrs-19.3.0-py2.py3-none-any.whl", hash = "sha256:08a96c641c3a74e44eb59afb61a24f2cb9f4d7188748e76ba4bb5edfa3cb7d1c"},
-    {file = "attrs-19.3.0.tar.gz", hash = "sha256:f7b7ce16570fe9965acd6d30101a28f62fb4a7f9e926b3bbc9b61f8b04247e72"},
-]
 black = [
-    {file = "black-19.10b0-py36-none-any.whl", hash = "sha256:1b30e59be925fafc1ee4565e5e08abef6b03fe455102883820fe5ee2e4734e0b"},
-    {file = "black-19.10b0.tar.gz", hash = "sha256:c2edb73a08e9e0e6f65a0e6af18b059b8b1cdd5bef997d7a0b181df93dc81539"},
+    {file = "black-20.8b1-py3-none-any.whl", hash = "sha256:70b62ef1527c950db59062cda342ea224d772abdf6adc58b86a45421bab20a6b"},
+    {file = "black-20.8b1.tar.gz", hash = "sha256:1c02557aa099101b9d21496f8a914e9ed2222ef70336404eeeac8edba836fbea"},
 ]
 cfgv = [
     {file = "cfgv-3.1.0-py2.py3-none-any.whl", hash = "sha256:1ccf53320421aeeb915275a196e23b3b8ae87dea8ac6698b1638001d4a486d53"},
     {file = "cfgv-3.1.0.tar.gz", hash = "sha256:c8e8f552ffcc6194f4e18dd4f68d9aef0c0d58ae7e7be8c82bee3c5e9edfa513"},
 ]
 click = [
-    {file = "click-7.1.1-py2.py3-none-any.whl", hash = "sha256:e345d143d80bf5ee7534056164e5e112ea5e22716bbb1ce727941f4c8b471b9a"},
-    {file = "click-7.1.1.tar.gz", hash = "sha256:8a18b4ea89d8820c5d0c7da8a64b2c324b4dabb695804dbfea19b9be9d88c0cc"},
+    {file = "click-7.1.2-py2.py3-none-any.whl", hash = "sha256:dacca89f4bfadd5de3d7489b7c8a566eee0d3676333fbb50030263894c38c0dc"},
+    {file = "click-7.1.2.tar.gz", hash = "sha256:d2b5255c7c6349bc1bd1e59e08cd12acbbd63ce649f2588755783aa94dfb6b1a"},
 ]
 distlib = [
     {file = "distlib-0.3.0.zip", hash = "sha256:2e166e231a26b36d6dfe35a48c4464346620f8645ed0ace01ee31822b288de21"},
@@ -506,8 +498,13 @@ mccabe = [
     {file = "mccabe-0.6.1-py2.py3-none-any.whl", hash = "sha256:ab8a6258860da4b6677da4bd2fe5dc2c659cff31b3ee4f7f5d64e79735b80d42"},
     {file = "mccabe-0.6.1.tar.gz", hash = "sha256:dd8d182285a0fe56bace7f45b5e7d1a6ebcbf524e8f3bd87eb0f125271b8831f"},
 ]
+mypy-extensions = [
+    {file = "mypy_extensions-0.4.3-py2.py3-none-any.whl", hash = "sha256:090fedd75945a69ae91ce1303b5824f428daf5a028d2f6ab8a299250a846f15d"},
+    {file = "mypy_extensions-0.4.3.tar.gz", hash = "sha256:2d82818f5bb3e369420cb3c4060a7970edba416647068eb4c5343488a6c604a8"},
+]
 nodeenv = [
     {file = "nodeenv-1.3.5-py2.py3-none-any.whl", hash = "sha256:5b2438f2e42af54ca968dd1b374d14a1194848955187b0e5e4be1f73813a5212"},
+    {file = "nodeenv-1.3.5.tar.gz", hash = "sha256:7389d06a7ea50c80ca51eda1b185db7b9ec38af1304d12d8b8299d6218486e91"},
 ]
 pathspec = [
     {file = "pathspec-0.8.0-py2.py3-none-any.whl", hash = "sha256:7d91249d21749788d07a2d0f94147accd8f845507400749ea19c1ec9054a12b0"},
diff --git a/pyproject.toml b/pyproject.toml
index 40fc952..20764e5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,7 +29,7 @@ authors = ["Alexander Shishenko <alex@shishenko.com>"]
 python = "^3.8"
 aioredis = "^1.3.1"
 fastapi = "^0.55.1"
-black = "19.10b0"
+black = "20.8b1"
 flake8 = "3.8.3"
 starlette-exporter = "^0.4.0"
 hypercorn = "^0.10.1"