diff --git a/datafusion/functions-nested/src/flatten.rs b/datafusion/functions-nested/src/flatten.rs
index 3650b1f37b1b..9d2cb8a3f667 100644
--- a/datafusion/functions-nested/src/flatten.rs
+++ b/datafusion/functions-nested/src/flatten.rs
@@ -42,10 +42,17 @@ make_udf_expr_and_func!(
 );
 
 #[derive(Debug)]
-pub(super) struct Flatten {
+pub struct Flatten {
     signature: Signature,
     aliases: Vec<String>,
 }
+
+impl Default for Flatten {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl Flatten {
     pub fn new() -> Self {
         Self {
diff --git a/datafusion/functions-nested/src/length.rs b/datafusion/functions-nested/src/length.rs
index 084b37bf13a4..3f92cb3ebb21 100644
--- a/datafusion/functions-nested/src/length.rs
+++ b/datafusion/functions-nested/src/length.rs
@@ -43,10 +43,17 @@ make_udf_expr_and_func!(
 );
 
 #[derive(Debug)]
-pub(super) struct ArrayLength {
+pub struct ArrayLength {
     signature: Signature,
     aliases: Vec<String>,
 }
+
+impl Default for ArrayLength {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl ArrayLength {
     pub fn new() -> Self {
         Self {