diff --git a/pysisyphus/helpers.py b/pysisyphus/helpers.py
index af7d96ebe..1f0761032 100644
--- a/pysisyphus/helpers.py
+++ b/pysisyphus/helpers.py
@@ -51,6 +51,8 @@ def geom_from_xyz_file(xyz_fn, coord_type="cart", **coord_kwargs):
     kwargs.update(coord_kwargs)
     xyz_fn = str(xyz_fn)
     atoms, coords, comment = parse_xyz_file(xyz_fn, with_comment=True)
+    # Normally, xyz files are in Angstrom. If "IN_BOHR" is present
+    # in the comment, we interpret this file as in bohr.
     if "IN_BOHR" not in comment.split():
         coords *= ANG2BOHR
     geom = Geometry(