diff --git a/pyproject.toml b/pyproject.toml
index 08f7c04..caf7fae 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,8 +17,8 @@ falcon-swagger-ui = {git = "https://github.com/alanorth/falcon-swagger-ui.git",
 ipython = { version = "^7.18.1", python = "^3.7" }
 flake8 = "^3.8.4"
 pytest = "^6.1.1"
-isort = "^5.5.4"
-black = "^20.8b1"
+black = {version = "^21.6b0", python = ">=3.6.2"}
+isort = {version = "^5.9.1", python = ">=3.6.1"}
 
 [build-system]
 requires = ["poetry>=0.12"]