diff --git a/tsflex/features/utils.py b/tsflex/features/utils.py
index c08dd3fe..a762dc5a 100644
--- a/tsflex/features/utils.py
+++ b/tsflex/features/utils.py
@@ -120,7 +120,7 @@ def wrap_func(*series: Union[np.ndarray, pd.Series], **kwargs) -> FuncWrapper:
         if not passthrough_nans:
             series = [s[~np.isnan(s)] for s in series]
         if any([len(s) < min_nb_samples for s in series]):
-            if not isinstance(output_names, list):
+            if not isinstance(output_names, list) or len(output_names) == 1:
                 return error_val
             return tuple([error_val] * len(output_names))
         return func(*series, **kwargs)