diff --git a/eth2/types/src/beacon_block/mod.rs b/eth2/types/src/beacon_block/mod.rs
index 9b58b27ee2..c736c07353 100644
--- a/eth2/types/src/beacon_block/mod.rs
+++ b/eth2/types/src/beacon_block/mod.rs
@@ -20,9 +20,7 @@ pub struct BeaconBlock {
 
 impl BeaconBlock {
     pub fn canonical_root(&self) -> Hash256 {
-        // TODO: implement tree hashing.
-        // https://github.com/sigp/lighthouse/issues/70
-        Hash256::from(&canonical_hash(&ssz_encode(self))[..])
+        Hash256::from(&self.hash_tree_root()[..])
     }
 }
 
diff --git a/eth2/types/src/beacon_state/mod.rs b/eth2/types/src/beacon_state/mod.rs
index 32cc7d829c..f8f458ae17 100644
--- a/eth2/types/src/beacon_state/mod.rs
+++ b/eth2/types/src/beacon_state/mod.rs
@@ -64,9 +64,7 @@ pub struct BeaconState {
 
 impl BeaconState {
     pub fn canonical_root(&self) -> Hash256 {
-        // TODO: implement tree hashing.
-        // https://github.com/sigp/lighthouse/issues/70
-        Hash256::from(&canonical_hash(&ssz_encode(self))[..])
+        Hash256::from(&self.hash_tree_root()[..])
     }
 }