diff --git a/crates/committer/src/hash/types.rs b/crates/committer/src/hash/types.rs
index 5b9ebeeb..95315659 100644
--- a/crates/committer/src/hash/types.rs
+++ b/crates/committer/src/hash/types.rs
@@ -6,6 +6,7 @@ use crate::types::Felt;
 pub(crate) struct HashInputPair(pub Felt, pub Felt);
 
 #[allow(dead_code)]
+#[derive(Clone, Copy)]
 pub(crate) struct HashOutput(pub Felt);
 
 #[allow(dead_code)]
diff --git a/crates/committer/src/patricia_merkle_tree/errors.rs b/crates/committer/src/patricia_merkle_tree/errors.rs
index f276d5a3..49c6aba4 100644
--- a/crates/committer/src/patricia_merkle_tree/errors.rs
+++ b/crates/committer/src/patricia_merkle_tree/errors.rs
@@ -5,5 +5,6 @@ pub(crate) enum CurrentSkeletonTreeError {}
 #[derive(Debug)]
 pub(crate) enum UpdatedSkeletonTreeError {}
 
-#[derive(Debug)]
-pub(crate) enum FilledTreeError {}
+pub(crate) enum FilledTreeError {
+    MissingRoot,
+}
diff --git a/crates/committer/src/patricia_merkle_tree/filled_node.rs b/crates/committer/src/patricia_merkle_tree/filled_node.rs
index 6cd72000..e82d2693 100644
--- a/crates/committer/src/patricia_merkle_tree/filled_node.rs
+++ b/crates/committer/src/patricia_merkle_tree/filled_node.rs
@@ -9,7 +9,7 @@ pub(crate) struct Nonce(pub Felt);
 #[allow(dead_code)]
 /// A node in a Patricia-Merkle tree which was modified during an update.
 pub(crate) struct FilledNode<L: LeafDataTrait> {
-    hash: HashOutput,
+    pub(crate) hash: HashOutput,
     data: NodeData<L>,
 }
 
diff --git a/crates/committer/src/patricia_merkle_tree/filled_tree.rs b/crates/committer/src/patricia_merkle_tree/filled_tree.rs
index 612b5ddd..7e0c04c2 100644
--- a/crates/committer/src/patricia_merkle_tree/filled_tree.rs
+++ b/crates/committer/src/patricia_merkle_tree/filled_tree.rs
@@ -2,10 +2,10 @@ use std::collections::HashMap;
 use std::collections::HashSet;
 use std::sync::Mutex;
 
+use crate::hash::types::HashOutput;
 use crate::patricia_merkle_tree::errors::FilledTreeError;
 use crate::patricia_merkle_tree::filled_node::FilledNode;
-use crate::patricia_merkle_tree::types::LeafDataTrait;
-use crate::patricia_merkle_tree::types::NodeIndex;
+use crate::patricia_merkle_tree::types::{LeafDataTrait, NodeIndex};
 use crate::storage::storage_trait::Storage;
 
 /// Consider a Patricia-Merkle Tree which has been updated with new leaves.
@@ -29,4 +29,11 @@ impl<L: LeafDataTrait> FilledTreeImpl<L> {
     fn get_all_nodes(&self) -> &HashMap<NodeIndex, Mutex<FilledNode<L>>> {
         &self.tree_map
     }
+
+    fn get_root_hash(&self) -> Result<HashOutput, FilledTreeError> {
+        match self.tree_map.get(&NodeIndex::root_index()) {
+            Some(root_node) => Ok(root_node.lock().expect("Lock poisned.").hash),
+            None => Err(FilledTreeError::MissingRoot),
+        }
+    }
 }
diff --git a/crates/committer/src/patricia_merkle_tree/types.rs b/crates/committer/src/patricia_merkle_tree/types.rs
index aebfa03c..7ec32b64 100644
--- a/crates/committer/src/patricia_merkle_tree/types.rs
+++ b/crates/committer/src/patricia_merkle_tree/types.rs
@@ -15,7 +15,7 @@ pub(crate) trait TreeHashFunction<L: LeafDataTrait, H: HashFunction> {
 }
 
 #[allow(dead_code)]
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub(crate) struct NodeIndex(pub Felt);
 
 #[allow(dead_code)]