diff --git a/src/flow/binary/balancing.rs b/src/flow/binary/balancing.rs
index 26b898a..23aab1f 100644
--- a/src/flow/binary/balancing.rs
+++ b/src/flow/binary/balancing.rs
@@ -39,8 +39,7 @@ impl<'a, BT: FunctorContext<'a>> FunctorContext<'a> for BalancedTrees<BT> {
 
 #[derive(Debug)]
 pub enum BalancingError {
-    LeafHeight(u64),
-    NodeHeight,
+    Height(HeightError),
     Balance(u64, u64),
     HeightOverflow,
     HeightMismatch { children: (u64, u64), parent: u64 },
@@ -49,10 +48,7 @@ pub enum BalancingError {
 impl Display for BalancingError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Self::NodeHeight => write!(f, "invalid AVL non-leaf height: 0."),
-            Self::LeafHeight(height) => {
-                write!(f, "invalid AVL leaf height: {height}!=0.")
-            }
+            Self::Height(height_error) => write!(f, "invalid AVL non-leaf height: {height_error}"),
             Self::Balance(hl, hr) => write!(f, "unbalanced AVL node: {hl} {hr}."),
             Self::HeightOverflow => write!(f, "AVL tree height overflow"),
             Self::HeightMismatch { children, parent } => {
diff --git a/src/rstd/collections/avl.rs b/src/rstd/collections/avl.rs
index bfa877c..99cdaa2 100644
--- a/src/rstd/collections/avl.rs
+++ b/src/rstd/collections/avl.rs
@@ -3,7 +3,7 @@ pub mod context;
 
 use std::{error::Error, fmt::Display, rc::Rc};
 
-use crate::flow::binary::balancing::*;
+use crate::flow::binary::{balancing::*, *};
 use crate::rcore::*;
 use crate::rstd::{
     atomic::{au64::*, *},
@@ -37,6 +37,12 @@ impl<E> From<BalancingError> for AvlError<E> {
     }
 }
 
+impl<E> From<HeightError> for AvlError<E> {
+    fn from(value: HeightError) -> Self {
+        BalancingError::Height(value).into()
+    }
+}
+
 impl<E: Display> Display for AvlError<E> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
@@ -173,10 +179,10 @@ impl<'a, Ctx: Context<'a>, F: Factory<'a, Ctx>> Factory<'a, Ctx> for AvlTreeFact
         let height = u64::a_deserialize(deserializer)?;
         if let Nullable::Null(_) = node {
             if height != 0 {
-                Err(BalancingError::LeafHeight(height))?
+                Err(HeightError::LeafHeight(height))?
             }
         } else if height == 0 {
-            Err(BalancingError::NodeHeight)?
+            Err(HeightError::NodeHeight)?
         }
         Ok(AvlTree { node, height })
     }