diff --git a/q2_diversity/_alpha/_visualizer.py b/q2_diversity/_alpha/_visualizer.py
index d8522c8..3bf8e2e 100644
--- a/q2_diversity/_alpha/_visualizer.py
+++ b/q2_diversity/_alpha/_visualizer.py
@@ -377,9 +377,9 @@ def alpha_rarefaction(output_dir: str, table: biom.Table, max_depth: int,
             raise ValueError("All metadata filtered after dropping columns "
                              "that contained non-categorical data.")
         metadata_df.columns = pd.MultiIndex.from_tuples(
-            [(c, '') for c in metadata_df.columns])
+            [(c, '') for c in metadata_df.columns],
+            names=('_alpha_rarefaction_depth_column_', 'iter'))
         columns = metadata_df.columns.get_level_values(0)
-
     data = _compute_rarefaction_data(table, min_depth, max_depth,
                                      steps, iterations, phylogeny, metrics)