diff --git a/pkgs/development/python-modules/cynthion/default.nix b/pkgs/development/python-modules/cynthion/default.nix
index ebaaea6079cf..a99fa93099bd 100644
--- a/pkgs/development/python-modules/cynthion/default.nix
+++ b/pkgs/development/python-modules/cynthion/default.nix
@@ -51,6 +51,8 @@ buildPythonPackage rec {
     setuptools
   ];
 
+  pythonRelaxDeps = [ "pygreat" ];
+
   pythonRemoveDeps = [ "future" ];
 
   dependencies = [