diff --git a/laborious/activities/mlflow.py b/laborious/activities/mlflow.py
index e6c75e1..e6522f0 100644
--- a/laborious/activities/mlflow.py
+++ b/laborious/activities/mlflow.py
@@ -149,6 +149,8 @@ class MLFlow(MinioManager):
         data.columns.name = None
         data.index.name = None
 
+        data['timestamp'] = data.index
+
         self.debug(f'Processed input data: \n {data.to_csv()}', metadata)
 
         # Request transformation from MLFlow model
diff --git a/laborious/utils/models/minio_dataframe_payload.py b/laborious/utils/models/minio_dataframe_payload.py
index 9d2fe48..c49218d 100644
--- a/laborious/utils/models/minio_dataframe_payload.py
+++ b/laborious/utils/models/minio_dataframe_payload.py
@@ -194,7 +194,7 @@ class MinioDataFramePayload:
             MinioDataFramePayload: Instance with data and/or MinIO fields set.
         """
 
-        if not dataframe or dataframe.empty:
+        if dataframe is None or dataframe.empty:
             return cls(
                 data=None, last_timestamp=now().strftime(DATETIME_FORMAT_WITH_TZ), status=status
             )