diff --git a/crates/connect/src/functions/mod.rs b/crates/connect/src/functions/mod.rs
index 4884939..89892ba 100644
--- a/crates/connect/src/functions/mod.rs
+++ b/crates/connect/src/functions/mod.rs
@@ -1108,7 +1108,21 @@ gen_func!(stddev, [col: Column], "Alias for stddev_samp.");
 gen_func!(stddev_pop, [col: Column], "Returns population standard deviation of the expression in a group.");
 gen_func!(stddev_samp, [col: Column], "Returns the unbiased sample standard deviation of the expression in a group.");
 gen_func!(sum, [col: Column], "Returns the sum of all values in the expression.");
-gen_func!(sum_distinct, [col: Column], "Returns the sum of distinct values in the expression.");
+
+/// "Returns the sum of distinct values in the expression."
+pub fn sum_distinct(col: impl Into<Column>) -> Column {
+    Column::from(spark::Expression {
+        expr_type: Some(spark::expression::ExprType::UnresolvedFunction(
+            spark::expression::UnresolvedFunction {
+                function_name: "sum".to_string(),
+                arguments: VecExpression::from_iter(vec![col]).into(),
+                is_distinct: true,
+                is_user_defined_function: false,
+            },
+        )),
+    })
+}
+
 gen_func!(var_pop, [col: Column], "Returns the population variance of the values in a group.");
 gen_func!(var_samp, [col: Column], "Returns the unbiased sample variance of the values in a group.");
 gen_func!(variance, [col: Column], "Alias for var_samp");
@@ -2546,4 +2560,42 @@ mod tests {
         assert_eq!(expected, res);
         Ok(())
     }
+
+    // Test aggregate functions
+    #[tokio::test]
+    async fn test_func_sum_distinct() -> Result<(), SparkError> {
+        let spark = setup().await;
+        let select_func = |df: DataFrame| {
+            df.select([sum_distinct(col("value")).alias("sum")])
+                .collect()
+        };
+        let record_batch_func =
+            |col: ArrayRef| RecordBatch::try_from_iter_with_nullable(vec![("sum", col, true)]);
+
+        let df = spark
+            .sql("SELECT * FROM VALUES (1), (2), (3), (1), (2), (3) AS data(value)")
+            .await?;
+        let res = select_func(df).await?;
+        let expected_col: ArrayRef = Arc::new(Int64Array::from(vec![6]));
+        let expected = record_batch_func(expected_col)?;
+        assert_eq!(expected, res);
+
+        let df = spark
+            .sql("SELECT * FROM VALUES (1), (2), (3), (null), (1), (2), (3) AS data(value)")
+            .await?;
+        let res = select_func(df).await?;
+        let expected_col: ArrayRef = Arc::new(Int64Array::from(vec![6]));
+        let expected = record_batch_func(expected_col)?;
+        assert_eq!(expected, res);
+
+        let df = spark
+            .sql("SELECT * FROM VALUES (null), (null), (null) AS data(value)")
+            .await?;
+        let res = select_func(df).await?;
+        let expected_col: ArrayRef = Arc::new(Float64Array::from(vec![None]));
+        let expected = record_batch_func(expected_col)?;
+        assert_eq!(expected, res);
+
+        Ok(())
+    }
 }