diff --git a/src/pytorch_tabular/tabular_datamodule.py b/src/pytorch_tabular/tabular_datamodule.py
index 8428722b..5241a395 100644
--- a/src/pytorch_tabular/tabular_datamodule.py
+++ b/src/pytorch_tabular/tabular_datamodule.py
@@ -290,11 +290,11 @@ def _update_config(self, config) -> InferredConfig:
             raise ValueError(f"{config.task} is an unsupported task.")
         if self.train is not None:
             categorical_cardinality = [
-                int(self.train[col].fillna("NA").nunique()) + 1 for col in config.categorical_cols
+                int(x) + 1 for x in list(self.train[config.categorical_cols].fillna("NA").nunique().values)
             ]
         else:
             categorical_cardinality = [
-                int(self.train_dataset.data[col].nunique()) + 1 for col in config.categorical_cols
+                int(x) + 1 for x in list(self.train_dataset.data[config.categorical_cols].nunique().values)
             ]
         if getattr(config, "embedding_dims", None) is not None:
             embedding_dims = config.embedding_dims