diff --git a/tzis/tzis.py b/tzis/tzis.py
index c00727dd63f15e99a621b4a768db0267e4020453..c46f71321a5445f4936782c55449bc4b88ae60bc 100644
--- a/tzis/tzis.py
+++ b/tzis/tzis.py
@@ -792,7 +792,7 @@ class write_zarr(fsspec.FSMap):
                 else:
                     first_attr = list(self.mf_dset.attrs.keys())[0]
                     self.provenance.gen_input(
-                        f"input_{first_attr}", self.mf_dset.attrs[first_attr]
+                        f"input_{first_attr}", [str(self.mf_dset.attrs[first_attr])]
                     )
             elif self.verbose:
                 print("Cannot create input provenance because no attrs given.")