diff --git a/pymc/data.py b/pymc/data.py
index d75fd698b8..0b18f2232a 100644
--- a/pymc/data.py
+++ b/pymc/data.py
@@ -234,7 +234,7 @@ def determine_coords(
             for dim in dims:
                 dim_name = dim
                 # str is applied because dim entries may be None
-                coords[str(dim_name)] = value[dim].to_numpy()
+                coords[str(dim_name)] = cast(xr.DataArray, value[dim]).to_numpy()
 
     if isinstance(value, np.ndarray) and dims is not None:
         if len(dims) != value.ndim: