diff --git a/swiftest/simulation_class.py b/swiftest/simulation_class.py
index adbc19bb9..b8218924d 100644
--- a/swiftest/simulation_class.py
+++ b/swiftest/simulation_class.py
@@ -2421,7 +2421,8 @@ def add_body(self,
                  rot: List[float] | List[npt.NDArray[np.float_]] | npt.NDArray[np.float_] | None=None,
                  Ip: List[float] | npt.NDArray[np.float_] | None=None,
                  J2: float | List[float] | npt.NDArray[np.float_] | None=None,
-                 J4: float | List[float] | npt.NDArray[np.float_] | None=None
+                 J4: float | List[float] | npt.NDArray[np.float_] | None=None,
+                 c_lm: List[float] | List[npt.NDArray[np.float_]] | npt.NDArray[np.float_] | None = None
                  ) -> None:
         """
         Adds a body (test particle or massive body) to the internal DataSet given a set up 6 vectors (orbital elements