diff --git a/pkgs/development/python-modules/pendulum/default.nix b/pkgs/development/python-modules/pendulum/default.nix
index 272d800e46d1..b2839e36177e 100644
--- a/pkgs/development/python-modules/pendulum/default.nix
+++ b/pkgs/development/python-modules/pendulum/default.nix
@@ -56,7 +56,9 @@ buildPythonPackage rec {
     python-dateutil
     tzdata
   ]
-  ++ lib.optional (!isPyPy) [ time-machine ]
+  ++ lib.optionals (!isPyPy) [
+    time-machine
+  ]
   ++ lib.optionals (pythonOlder "3.9") [
     importlib-resources
   ];