diff --git a/lighthouse/state/mod.rs b/lighthouse/state/mod.rs
index d10acf8fda..737839721d 100644
--- a/lighthouse/state/mod.rs
+++ b/lighthouse/state/mod.rs
@@ -1,10 +1,11 @@
 extern crate rlp;
 extern crate ethereum_types;
-extern crate blake2;
+extern crate blake2_rfc as blake2;
 extern crate bytes;
 extern crate ssz;
 
 use super::utils;
+use super::db;
 
 pub mod active_state;
 pub mod attestation_record;
diff --git a/lighthouse/state/transition/mod.rs b/lighthouse/state/transition/mod.rs
index dd8967e652..8ba28d05f7 100644
--- a/lighthouse/state/transition/mod.rs
+++ b/lighthouse/state/transition/mod.rs
@@ -1,7 +1,13 @@
 use super::super::utils::types::Hash256;
+use super::crystallized_state;
+use super::super::db;
+use super::ssz;
+use super::blake2;
+use super::utils;
 
 mod attestation_parent_hashes;
 mod shuffling;
+mod validate_block;
 
 pub use self::attestation_parent_hashes::attestation_parent_hashes;
 pub use self::shuffling::shuffle;
diff --git a/lighthouse/state/transition/validate_block.rs b/lighthouse/state/transition/validate_block.rs
new file mode 100644
index 0000000000..bbd784d327
--- /dev/null
+++ b/lighthouse/state/transition/validate_block.rs
@@ -0,0 +1,4 @@
+enum BlockStatus {
+    NewBlock,
+    KnownBlock,
+}
diff --git a/lighthouse/utils/mod.rs b/lighthouse/utils/mod.rs
index d116422be5..cfb302d4b4 100644
--- a/lighthouse/utils/mod.rs
+++ b/lighthouse/utils/mod.rs
@@ -1,8 +1,9 @@
 extern crate ethereum_types;
-extern crate blake2;
+extern crate blake2_rfc as blake2;
 extern crate crypto_mac;
 extern crate boolean_bitfield;
 
+pub mod hash;
 pub mod types;
 pub mod bls;
 pub mod test_helpers;
diff --git a/lighthouse/utils/types.rs b/lighthouse/utils/types.rs
index 8e9bf2006e..949b7a549d 100644
--- a/lighthouse/utils/types.rs
+++ b/lighthouse/utils/types.rs
@@ -3,7 +3,6 @@ extern crate boolean_bitfield;
 use super::ethereum_types::{ H256, H160 };
 use self::boolean_bitfield::BooleanBitfield;
 
-pub use super::blake2::Blake2s;
 pub use super::ethereum_types::U256;
 
 pub type Hash256 = H256;