diff --git a/src/ai_models_graphcast/output.py b/src/ai_models_graphcast/output.py
index f46b326..0a4d2b5 100644
--- a/src/ai_models_graphcast/output.py
+++ b/src/ai_models_graphcast/output.py
@@ -39,9 +39,9 @@ def save_output_xarray(
 
     for time in range(lead_time // hour_steps):
         for fs in all_fields[: len(all_fields) // len(lagged)]:
-            param, level = fs.metadata("shortName"), fs.metadata("levelist", default=0)
+            param, level = fs.metadata("shortName"), fs.metadata("levelist", default=None)
 
-            if level != 0:
+            if level is not None:
                 param = GRIB_TO_XARRAY_PL.get(param, param)
                 if param not in target_variables:
                     continue