diff --git a/storage/src/nullifier_sparse_merkle_tree.rs b/storage/src/nullifier_sparse_merkle_tree.rs
index 6301125..dd8ec95 100644
--- a/storage/src/nullifier_sparse_merkle_tree.rs
+++ b/storage/src/nullifier_sparse_merkle_tree.rs
@@ -120,3 +120,16 @@ impl Default for NullifierSparseMerkleTree {
         Self::new()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::nullifier::UTXONullifier;
+    use monotree::database::MemoryDB;
+    use monotree::hasher::Blake3;
+    use monotree::Monotree;
+
+    fn create_nullifier(hash: TreeHashType) -> UTXONullifier {
+        UTXONullifier { utxo_hash: hash }
+    }
+}