diff --git a/pyproject.toml b/pyproject.toml
index 2a2b459..f104c69 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -6,7 +6,7 @@ target-version = ['py310']
 
 [tool.mypy]
 #python-executable = 'pypy3'
-python-version = 3.10
+python-version = '3.10'
 
 # https://black.readthedocs.io/en/stable/guides/using_black_with_other_tools.html