diff --git a/pysparky/utils.py b/pysparky/utils.py
index 6a7f2ab..248e956 100644
--- a/pysparky/utils.py
+++ b/pysparky/utils.py
@@ -24,37 +24,41 @@ def create_map_from_dict(dict_: dict[str, int]) -> Column:
     return F.create_map(list(map(F.lit, itertools.chain(*dict_.items()))))
 
 
-def join_dataframes_on_column(
-    column_name: str, dataframes: list[DataFrame]
-) -> DataFrame:
+def join_dataframes_on_column(column_name: str, *dataframes: DataFrame) -> DataFrame:
     """
     Joins a list of DataFrames on a specified column using an outer join.
 
     Args:
         column_name (str): The column name to join on.
-        dataframes (list): A list of DataFrames to join.
+        *dataframes (DataFrame): A list of DataFrames to join.
 
     Returns:
         DataFrame: The resulting DataFrame after performing the outer joins.
     """
+    if not dataframes:
+        raise ValueError("At least one DataFrame must be provided")
+
     joined_df = dataframes[0].select(F.col(column_name))
     for sdf in dataframes:
         joined_df = joined_df.join(sdf, column_name, "outer").fillna(0)
     return joined_df
 
 
-def union_dataframes(dataframes: list[DataFrame]) -> DataFrame:
+def union_dataframes(*dataframes: DataFrame) -> DataFrame:
     """
     Unions a list of DataFrames.
 
     Args:
-        dataframes (list): A list of DataFrames to union.
+        *dataframes (DataFrame): A list of DataFrames to union.
 
     Returns:
         DataFrame: The resulting DataFrame after performing the unions.
     """
     # TODO: Check on the schema, if not align, raise error
 
+    if not dataframes:
+        raise ValueError("At least one DataFrame must be provided")
+
     output_df = dataframes[0]
     for sdf in dataframes[1:]:
         output_df = output_df.union(sdf)
diff --git a/tests/test_utils.py b/tests/test_utils.py
index cbe60b9..c430b32 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -39,7 +39,7 @@ def test_join_dataframes_on_column(spark):
 
     dataframes = [df1, df2, df3]
 
-    result_df = utils.join_dataframes_on_column("id", dataframes)
+    result_df = utils.join_dataframes_on_column("id", *dataframes)
     result_data = result_df.collect()
 
     expected_data = [
@@ -58,6 +58,11 @@ def test_join_dataframes_on_column(spark):
     assert result_data == expected_result
 
 
+def test_join_dataframes_on_column_no_input():
+    with pytest.raises(ValueError, match="At least one DataFrame must be provided"):
+        utils.join_dataframes_on_column("col")
+
+
 def test_union_dataframes(spark):
     data1 = {"id": [1, 2, 3], "value": [10, 20, 30]}
     data2 = {"id": [4, 5, 6], "value": [40, 50, 60]}
@@ -69,7 +74,7 @@ def test_union_dataframes(spark):
 
     dataframes = [df1, df2, df3]
 
-    result_df = utils.union_dataframes(dataframes)
+    result_df = utils.union_dataframes(*dataframes)
     result_data = result_df.collect()
 
     expected_data = [
@@ -90,5 +95,10 @@ def test_union_dataframes(spark):
     assert result_data == expected_result
 
 
+def test_union_dataframes_no_input():
+    with pytest.raises(ValueError, match="At least one DataFrame must be provided"):
+        utils.union_dataframes()
+
+
 if __name__ == "__main__":
     pytest.main([__file__])