diff --git a/storage/src/lib.rs b/storage/src/lib.rs
index 3c25db95..b21c8d44 100644
--- a/storage/src/lib.rs
+++ b/storage/src/lib.rs
@@ -25,7 +25,7 @@ mod transaction_meta;
 mod transaction_provider;
 mod nullifier;
 mod tree_state;
-mod anchor;
+mod tree_state_provider;
 
 pub use primitives::{hash, bytes};
 
@@ -42,7 +42,7 @@ pub use transaction_meta::TransactionMeta;
 pub use transaction_provider::{TransactionProvider, TransactionOutputProvider, TransactionMetaProvider};
 pub use nullifier::{Nullifier, NullifierTracker};
 pub use tree_state::{TreeState, H32 as H32TreeDim, Dim as TreeDim, RegularTreeState};
-pub use anchor::AnchorProvider;
+pub use tree_state_provider::TreeStateProvider;
 
 /// Epoch tag.
 ///
diff --git a/storage/src/anchor.rs b/storage/src/tree_state_provider.rs
similarity index 62%
rename from storage/src/anchor.rs
rename to storage/src/tree_state_provider.rs
index c0d69d9c..0e2eaa50 100644
--- a/storage/src/anchor.rs
+++ b/storage/src/tree_state_provider.rs
@@ -2,7 +2,7 @@ use hash::H256;
 use bytes::Bytes;
 use {EpochTag, RegularTreeState};
 
-pub trait AnchorProvider {
+pub trait TreeStateProvider {
 	fn tree_bytes_at(&self, root: &H256) -> Option<Bytes>;
 
 	fn tree_at(&self, root: &H256) -> Option<RegularTreeState> {
@@ -13,4 +13,10 @@ pub trait AnchorProvider {
 					.expect("Corrupted database: wrong tree state format!")
 			)
 	}
+
+	fn block_root(&self, block_hash: &H256) -> Option<H256>;
+
+	fn tree_at_block(&self, block_hash: &H256) -> Option<RegularTreeState> {
+		self.block_root(block_hash).and_then(|h| self.tree_at(&h))
+	}
 }