diff --git a/pyproject.toml b/pyproject.toml
index 236ee6233..f423ceb9d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,6 +41,8 @@ embit = "0.7.0"
 secp256k1 = "0.14.0"
 # keep for backwards compatibility with lnurlp and cashu
 environs = "9.5.0"
+# needed for scheduler extension
+python-crontab = "3.0.0"
 
 [tool.poetry.group.dev.dependencies]
 black = "^23.7.0"