diff --git a/pkgs/development/python-modules/weatherflow4py/default.nix b/pkgs/development/python-modules/weatherflow4py/default.nix
index 7bb1530056fa..35e4e1883e86 100644
--- a/pkgs/development/python-modules/weatherflow4py/default.nix
+++ b/pkgs/development/python-modules/weatherflow4py/default.nix
@@ -36,6 +36,8 @@ buildPythonPackage rec {
     websockets
   ];
 
+  pythonRelaxDeps = [ "marshmallow" ];
+
   nativeCheckInputs = [
     aioresponses
     pytest-asyncio