diff --git a/deploy-chatmail/pyproject.toml b/deploy-chatmail/pyproject.toml
index 7b6b243a..39eed1d8 100644
--- a/deploy-chatmail/pyproject.toml
+++ b/deploy-chatmail/pyproject.toml
@@ -13,6 +13,7 @@ dependencies = [
   "pytest",
   "setuptools>=68",
   "termcolor",
+  "build",
   "tox",
 ]