diff --git a/pkgs/by-name/pr/prefect/package.nix b/pkgs/by-name/pr/prefect/package.nix
index 752b6d9f8baf..31ae575004a0 100644
--- a/pkgs/by-name/pr/prefect/package.nix
+++ b/pkgs/by-name/pr/prefect/package.nix
@@ -86,6 +86,7 @@ python3Packages.buildPythonApplication rec {
       ujson
       uvicorn
       websockets
+      whenever
       uv
     ]
     ++ sqlalchemy.optional-dependencies.asyncio