diff --git a/src/triefile/mod.rs b/src/triefile/mod.rs
index 18fa433..c5d7c91 100644
--- a/src/triefile/mod.rs
+++ b/src/triefile/mod.rs
@@ -107,7 +107,7 @@ impl<const Z:usize> TrieFile<Z> {
         }
     }
 
-    pub async fn set(&mut self, key:&[u8], data:&[u8]) -> Result<(),std::io::Error>
+    pub async fn set(&mut self, key:&[u8], data:&[u8]) -> Result<usize,std::io::Error>
     {
         let mut node = Node::<Z>::new();
 
@@ -115,11 +115,13 @@ impl<const Z:usize> TrieFile<Z> {
         let mut key_index = 0;
         let mut parent_index = u32::MAX;
 
+        let mut result = 0;
+
         // Allocate first chain of nodes if none exist.
         if self.block_count().await? == 0 {
             //println!("originate");
-            self.trailing_nodes(key, &mut key_index, data, u32::MAX).await?;
-            return Ok(());
+            result = self.trailing_nodes(key, &mut key_index, data, u32::MAX).await? as usize;
+            return Ok(result);
         } else {
             //println!("traverse");
 
@@ -158,6 +160,7 @@ impl<const Z:usize> TrieFile<Z> {
                             }
 
                             self.write_node(node_index, &node).await?;
+                            result = node_index as usize;
                         }
 
                         // Continue to child node.
@@ -173,6 +176,7 @@ impl<const Z:usize> TrieFile<Z> {
                                 //println!(" - new child");
 
                                 node.child = self.trailing_nodes(key, &mut key_index, data, node_index).await?;
+                                result = node.child as usize;
                                 self.write_node(node_index, &node).await?;
                             }
                         }
@@ -213,6 +217,7 @@ impl<const Z:usize> TrieFile<Z> {
                         // Write data to trailing nodes.
                         if key_index < key.len() {
                             let new_branch = self.trailing_nodes(key, &mut key_index, data, node_index).await?;
+                            result = new_branch as usize;
                             child_node.next = new_branch;
                         }
                         
@@ -222,6 +227,7 @@ impl<const Z:usize> TrieFile<Z> {
                             for i in 0..Z.min(data.len()) {
                                 node.data[i] = data[i];
                             }
+                            result = node_index as usize;
                         }
 
                         self.write_node(node_index, &node).await?;
@@ -242,13 +248,14 @@ impl<const Z:usize> TrieFile<Z> {
 
                         // Allocate and initialize subsequent nodes until key is resolved.
                         node.next = self.trailing_nodes(key, &mut key_index, data, parent_index).await?;
+                        result = node.next as usize;
                         self.write_node(node_index, &node).await?;
                     }
                 }
             }
         }
 
-        Ok(())
+        Ok(result)
     }
 
     pub async fn find(&self, key:&[u8]) -> Result<Option<usize>, std::io::Error>