diff --git a/pyproject.toml b/pyproject.toml
index 959b053..53f8083 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,5 +21,5 @@ mkdocs = "~1.0"
 mkdocs-material = "~4.2"
 
 [build-system]
-requires = ["poetry>=0.12"]
+requires = ["poetry==1.0","cryptography==2.7","setuptools==51.0.0","wheel==0.36.2"]
 build-backend = "poetry.masonry.api"