diff --git a/poetry.lock b/poetry.lock
index e0ed4690..5fb11266 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -22,7 +22,7 @@ tests_no_zope = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>
 
 [[package]]
 name = "black"
-version = "21.8b0"
+version = "21.9b0"
 description = "The uncompromising code formatter."
 category = "dev"
 optional = false
@@ -555,7 +555,7 @@ testing = ["pytest (>=4.6)", "pytest-checkdocs (>=2.4)", "pytest-flake8", "pytes
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.9"
-content-hash = "dec3915f2035a8c5211af1956057180bb81865064dd43628478701fa68ff2f15"
+content-hash = "852b2409730a86283c4e714b24868414c31643ec02d0532ab7b6a21cf46a87e6"
 
 [metadata.files]
 atomicwrites = [
@@ -567,8 +567,8 @@ attrs = [
     {file = "attrs-20.3.0.tar.gz", hash = "sha256:832aa3cde19744e49938b91fea06d69ecb9e649c93ba974535d08ad92164f700"},
 ]
 black = [
-    {file = "black-21.8b0-py3-none-any.whl", hash = "sha256:2a0f9a8c2b2a60dbcf1ccb058842fb22bdbbcb2f32c6cc02d9578f90b92ce8b7"},
-    {file = "black-21.8b0.tar.gz", hash = "sha256:570608d28aa3af1792b98c4a337dbac6367877b47b12b88ab42095cfc1a627c2"},
+    {file = "black-21.9b0-py3-none-any.whl", hash = "sha256:380f1b5da05e5a1429225676655dddb96f5ae8c75bdf91e53d798871b902a115"},
+    {file = "black-21.9b0.tar.gz", hash = "sha256:7de4cfc7eb6b710de325712d40125689101d21d25283eed7e9998722cf10eb91"},
 ]
 click = [
     {file = "click-8.0.1-py3-none-any.whl", hash = "sha256:fba402a4a47334742d782209a7c79bc448911afe1149d07bdabdf480b3e2f4b6"},
diff --git a/pyproject.toml b/pyproject.toml
index 30f61151..88542c99 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,7 +21,7 @@ mkdocs = "^1.2.1"
 mkdocs-material = "^7.2.6"
 
 [tool.poetry.dev-dependencies]
-black = "^21.8b0"
+black = "^21.9b0"
 codespell = "^2.1.0"
 flake8 = "^3.9.2"
 pep8-naming = "^0.12.1"