diff --git a/src/spatialdata/models/models.py b/src/spatialdata/models/models.py
index 60f4ee20..a4efd60e 100644
--- a/src/spatialdata/models/models.py
+++ b/src/spatialdata/models/models.py
@@ -885,7 +885,7 @@ def _add_metadata_and_validate(
             # It also just changes the state of the series, so it is not a big deal.
             if isinstance(data[c].dtype, CategoricalDtype) and not data[c].cat.known:
                 try:
-                    data[c] = data[c].cat.set_categories(data[c].head(1).cat.categories)
+                    data[c] = data[c].cat.set_categories(data[c].compute().cat.categories)
                 except ValueError:
                     logger.info(f"Column `{c}` contains unknown categories. Consider casting it.")