diff --git a/pyproject.toml b/pyproject.toml
index d541402..fe58ad4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,7 +38,7 @@ requests = "^2.31.0"
 [tool.poetry.group.dev.dependencies]
 black = ">=23.7,<25.0"
 flake8 = ">=6.1,<8.0"
-isort = "^5.12.0"
+isort = ">=5.12,<7.0"
 pre-commit = ">=3.3.3,<5.0.0"
 pysen = ">=0.10.5,<0.12.0"
 pytest = ">=7.4,<9.0"