diff --git a/pkgs/development/python-modules/diffenator2/default.nix b/pkgs/development/python-modules/diffenator2/default.nix
index 5dc3bbd3554a..111cf8aa2a83 100644
--- a/pkgs/development/python-modules/diffenator2/default.nix
+++ b/pkgs/development/python-modules/diffenator2/default.nix
@@ -42,6 +42,7 @@ buildPythonPackage rec {
   pythonRelaxDeps = [
     "protobuf"
     "python-bidi"
+    "youseedee"
   ];
 
   build-system = [