diff --git a/src/viur/core/bones/base.py b/src/viur/core/bones/base.py
index 94a9e0cc5..01fd939a8 100644
--- a/src/viur/core/bones/base.py
+++ b/src/viur/core/bones/base.py
@@ -389,7 +389,7 @@ def __setattr__(self, key, value):
             assignment.
         """
         if not self.isClonedInstance and getSystemInitialized() and key != "isClonedInstance" and not key.startswith(
-            "_"):
+                "_"):
             raise AttributeError("You cannot modify this Skeleton. Grab a copy using .clone() first")
         super().__setattr__(key, value)
 
@@ -1273,8 +1273,7 @@ def _compute(self, skel: 'viur.core.skeleton.SkeletonInstance', bone_name: str):
         compute_fn_parameters = inspect.signature(self.compute.fn).parameters
         compute_fn_args = {}
         if "skel" in compute_fn_parameters:
-            from viur.core.skeleton import skeletonByKind, \
-                RefSkel  # noqa: E402 # import works only here because circular imports
+            from viur.core.skeleton import skeletonByKind, RefSkel  # noqa: E402 # import works only here because circular imports
 
             if issubclass(skel.skeletonCls, RefSkel):  # we have a ref skel we must load the complete skeleton
                 cloned_skel = skeletonByKind(skel.kindName)()