diff --git a/rocketpy/mathutils/function.py b/rocketpy/mathutils/function.py
index f2323d613..1fca6b3ca 100644
--- a/rocketpy/mathutils/function.py
+++ b/rocketpy/mathutils/function.py
@@ -144,7 +144,11 @@ def set_source(self, source):
         self : Function
         """
         inputs, outputs, interpolation, extrapolation = self._check_user_input(
-            source, self.__inputs__, self.__outputs__, self.__interpolation__, self.__extrapolation__
+            source,
+            self.__inputs__,
+            self.__outputs__,
+            self.__interpolation__,
+            self.__extrapolation__,
         )
         # If the source is a Function
         if isinstance(source, Function):