diff --git a/pertpy/tools/_augur.py b/pertpy/tools/_augur.py
index d8d9c5cb..efc60b19 100644
--- a/pertpy/tools/_augur.py
+++ b/pertpy/tools/_augur.py
@@ -774,6 +774,7 @@ def predict(
             elif (
                 cell_type_subsample.obs.groupby(
                     ["cell_type", "label"],
+                    observed=True,
                 ).y_.count()
                 < subsample_size
             ).any():