diff --git a/crates/polars-core/src/frame/explode.rs b/crates/polars-core/src/frame/explode.rs
index c7ed14eca344..a405067d834c 100644
--- a/crates/polars-core/src/frame/explode.rs
+++ b/crates/polars-core/src/frame/explode.rs
@@ -24,8 +24,8 @@ fn get_exploded(series: &Series) -> PolarsResult<(Series, OffsetsBuffer<i64>)> {
 #[derive(Clone, Default, Debug, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde-lazy", derive(Serialize, Deserialize))]
 pub struct UnpivotArgs {
-    pub index: Vec<SmartString>,
     pub on: Vec<SmartString>,
+    pub index: Vec<SmartString>,
     pub variable_name: Option<SmartString>,
     pub value_name: Option<SmartString>,
     /// Whether the unpivot may be done
@@ -247,8 +247,8 @@ impl DataFrame {
         let index = index.into_vec();
         let on = on.into_vec();
         self.unpivot2(UnpivotArgs {
-            index,
             on,
+            index,
             ..Default::default()
         })
     }
@@ -448,8 +448,8 @@ mod test {
         );
 
         let args = UnpivotArgs {
-            index: vec![],
             on: vec![],
+            index: vec![],
             ..Default::default()
         };
 
@@ -464,8 +464,8 @@ mod test {
         );
 
         let args = UnpivotArgs {
-            index: vec!["A".into()],
             on: vec![],
+            index: vec!["A".into()],
             ..Default::default()
         };
 
diff --git a/crates/polars-lazy/src/tests/queries.rs b/crates/polars-lazy/src/tests/queries.rs
index 690dc6f57ea9..ade6df69c57e 100644
--- a/crates/polars-lazy/src/tests/queries.rs
+++ b/crates/polars-lazy/src/tests/queries.rs
@@ -50,8 +50,8 @@ fn test_lazy_unpivot() {
     let df = get_df();
 
     let args = UnpivotArgs {
-        index: vec!["petal_width".into(), "petal_length".into()],
         on: vec!["sepal_length".into(), "sepal_width".into()],
+        index: vec!["petal_width".into(), "petal_length".into()],
         ..Default::default()
     };
 
diff --git a/crates/polars-ops/src/frame/pivot/mod.rs b/crates/polars-ops/src/frame/pivot/mod.rs
index 194f3a2c5d69..11a2d0b64248 100644
--- a/crates/polars-ops/src/frame/pivot/mod.rs
+++ b/crates/polars-ops/src/frame/pivot/mod.rs
@@ -110,8 +110,8 @@ where
     let values = get_values_columns(pivot_df, &index, &on, values);
     pivot_impl(
         pivot_df,
-        &index,
         &on,
+        &index,
         &values,
         agg_fn,
         sort_columns,
@@ -153,8 +153,8 @@ where
     let values = get_values_columns(pivot_df, &index, &on, values);
     pivot_impl(
         pivot_df,
-        &index,
         &on,
+        &index,
         &values,
         agg_fn,
         sort_columns,
@@ -192,11 +192,11 @@ where
 fn pivot_impl(
     pivot_df: &DataFrame,
     // keys of the first group_by operation
+    on: &[String],
+    // these columns will be aggregated in the nested group_by
     index: &[String],
     // these columns will be used for a nested group_by
     // the rows of this nested group_by will be pivoted as header column values
-    on: &[String],
-    // these columns will be aggregated in the nested group_by
     values: &[String],
     // aggregation function
     agg_fn: Option<PivotAgg>,
diff --git a/py-polars/src/dataframe/general.rs b/py-polars/src/dataframe/general.rs
index 421afe0c5995..40978fe7427c 100644
--- a/py-polars/src/dataframe/general.rs
+++ b/py-polars/src/dataframe/general.rs
@@ -405,8 +405,8 @@ impl PyDataFrame {
         variable_name: Option<&str>,
     ) -> PyResult<Self> {
         let args = UnpivotArgs {
-            index: strings_to_smartstrings(index),
             on: strings_to_smartstrings(on),
+            index: strings_to_smartstrings(index),
             value_name: value_name.map(|s| s.into()),
             variable_name: variable_name.map(|s| s.into()),
             streamable: false,
diff --git a/py-polars/src/lazyframe/mod.rs b/py-polars/src/lazyframe/mod.rs
index 277a2c1980a7..ce18a4ea2f35 100644
--- a/py-polars/src/lazyframe/mod.rs
+++ b/py-polars/src/lazyframe/mod.rs
@@ -1121,8 +1121,8 @@ impl PyLazyFrame {
         streamable: bool,
     ) -> Self {
         let args = UnpivotArgs {
-            index: strings_to_smartstrings(index),
             on: strings_to_smartstrings(on),
+            index: strings_to_smartstrings(index),
             value_name: value_name.map(|s| s.into()),
             variable_name: variable_name.map(|s| s.into()),
             streamable,