diff --git a/weldx/transformations/types.py b/weldx/transformations/types.py
index 668bc6bd7..945fcd069 100644
--- a/weldx/transformations/types.py
+++ b/weldx/transformations/types.py
@@ -2,6 +2,7 @@
 
 from typing import Union
 
+import numpy as np
 import numpy.typing as npt
 import pint
 import xarray as xr
@@ -9,7 +10,7 @@
 
 types_coordinates = Union[xr.DataArray, npt.ArrayLike, pint.Quantity]
 types_orientation = Union[xr.DataArray, npt.ArrayLike, Rotation]
-types_homogeneous = Union[xr.DataArray, npt.ArrayLike]
+types_homogeneous = Union[xr.DataArray, np.ndarray]
 
 
 __all__ = [