diff --git a/pyproject.toml b/pyproject.toml
index 17de146..38306cf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,7 +14,7 @@ pytest = "^7.0.1"
 black = "^20.8b1"
 isort = "^5.8.0"
 autoflake = "^1.3.1"
-mypy = "^0.971"
+mypy = "^0.991"
 
 [build-system]
 requires = ["poetry>=0.12"]