diff --git a/pkgs/development/python-modules/pluthon/default.nix b/pkgs/development/python-modules/pluthon/default.nix
index 51f73a7381c6..1ff7d0530002 100644
--- a/pkgs/development/python-modules/pluthon/default.nix
+++ b/pkgs/development/python-modules/pluthon/default.nix
@@ -26,7 +26,7 @@ buildPythonPackage rec {
     setuptools
     uplc
     ordered-set
-  ] ++ lib.optionals (pythonOlder "3.9") graphlib-backport;
+  ] ++ lib.optional (pythonOlder "3.9") graphlib-backport;
 
   pythonImportsCheck = [ "pluthon" ];