diff --git a/src/viadot/sources/sap_rfc.py b/src/viadot/sources/sap_rfc.py
index 0006eb13..22d04ee0 100755
--- a/src/viadot/sources/sap_rfc.py
+++ b/src/viadot/sources/sap_rfc.py
@@ -1157,7 +1157,7 @@ def to_df(self, tests: dict | None = None) -> pd.DataFrame:  # noqa: C901, PLR09
                                 missing_whitespaces_len = (
                                     unique_column_len - actual_length_of_field
                                 )
-                                df.loc[rows_missing_whitespaces, col] += (
+                                df_tmp.loc[rows_missing_whitespaces, col] += (
                                     np.char.multiply(
                                         " ",
                                         missing_whitespaces_len[