diff --git a/eth2/utils/bls/src/aggregate_signature.rs b/eth2/utils/bls/src/aggregate_signature.rs
index f26bd2db6..0fbcc3493 100644
--- a/eth2/utils/bls/src/aggregate_signature.rs
+++ b/eth2/utils/bls/src/aggregate_signature.rs
@@ -6,7 +6,7 @@ use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::{encode as hex_encode, HexVisitor};
 use ssz::{decode, Decodable, DecodeError, Encodable, SszStream};
-use tree_hash::impl_tree_hash_for_ssz_bytes;
+use tree_hash::tree_hash_ssz_encoding_as_vector;
 
 /// A BLS aggregate signature.
 ///
@@ -166,7 +166,7 @@ impl<'de> Deserialize<'de> for AggregateSignature {
     }
 }
 
-impl_tree_hash_for_ssz_bytes!(AggregateSignature);
+tree_hash_ssz_encoding_as_vector!(AggregateSignature);
 
 #[cfg(test)]
 mod tests {
diff --git a/eth2/utils/bls/src/fake_aggregate_signature.rs b/eth2/utils/bls/src/fake_aggregate_signature.rs
index 602639b6b..f201eba3e 100644
--- a/eth2/utils/bls/src/fake_aggregate_signature.rs
+++ b/eth2/utils/bls/src/fake_aggregate_signature.rs
@@ -3,7 +3,7 @@ use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::{encode as hex_encode, PrefixedHexVisitor};
 use ssz::{ssz_encode, Decodable, DecodeError, Encodable, SszStream};
-use tree_hash::impl_tree_hash_for_ssz_bytes;
+use tree_hash::tree_hash_ssz_encoding_as_vector;
 
 /// A BLS aggregate signature.
 ///
@@ -99,7 +99,7 @@ impl<'de> Deserialize<'de> for FakeAggregateSignature {
     }
 }
 
-impl_tree_hash_for_ssz_bytes!(FakeAggregateSignature);
+tree_hash_ssz_encoding_as_vector!(FakeAggregateSignature);
 
 #[cfg(test)]
 mod tests {
diff --git a/eth2/utils/bls/src/fake_signature.rs b/eth2/utils/bls/src/fake_signature.rs
index b07dd66a5..3208ed992 100644
--- a/eth2/utils/bls/src/fake_signature.rs
+++ b/eth2/utils/bls/src/fake_signature.rs
@@ -4,7 +4,7 @@ use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::HexVisitor;
 use ssz::{ssz_encode, Decodable, DecodeError, Encodable, SszStream};
-use tree_hash::impl_tree_hash_for_ssz_bytes;
+use tree_hash::tree_hash_ssz_encoding_as_vector;
 
 /// A single BLS signature.
 ///
@@ -74,7 +74,7 @@ impl Decodable for FakeSignature {
     }
 }
 
-impl_tree_hash_for_ssz_bytes!(FakeSignature);
+tree_hash_ssz_encoding_as_vector!(FakeSignature);
 
 impl Serialize for FakeSignature {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
diff --git a/eth2/utils/bls/src/public_key.rs b/eth2/utils/bls/src/public_key.rs
index a553ee888..dcbbc622a 100644
--- a/eth2/utils/bls/src/public_key.rs
+++ b/eth2/utils/bls/src/public_key.rs
@@ -7,7 +7,7 @@ use ssz::{decode, ssz_encode, Decodable, DecodeError, Encodable, SszStream};
 use std::default;
 use std::fmt;
 use std::hash::{Hash, Hasher};
-use tree_hash::impl_tree_hash_for_ssz_bytes;
+use tree_hash::tree_hash_ssz_encoding_as_vector;
 
 /// A single BLS signature.
 ///
@@ -105,7 +105,7 @@ impl<'de> Deserialize<'de> for PublicKey {
     }
 }
 
-impl_tree_hash_for_ssz_bytes!(PublicKey);
+tree_hash_ssz_encoding_as_vector!(PublicKey);
 
 impl PartialEq for PublicKey {
     fn eq(&self, other: &PublicKey) -> bool {
diff --git a/eth2/utils/bls/src/secret_key.rs b/eth2/utils/bls/src/secret_key.rs
index 38fd2d379..d1aaa96da 100644
--- a/eth2/utils/bls/src/secret_key.rs
+++ b/eth2/utils/bls/src/secret_key.rs
@@ -5,7 +5,7 @@ use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::HexVisitor;
 use ssz::{decode, ssz_encode, Decodable, DecodeError, Encodable, SszStream};
-use tree_hash::impl_tree_hash_for_ssz_bytes;
+use tree_hash::tree_hash_ssz_encoding_as_vector;
 
 /// A single BLS signature.
 ///
@@ -70,7 +70,7 @@ impl<'de> Deserialize<'de> for SecretKey {
     }
 }
 
-impl_tree_hash_for_ssz_bytes!(SecretKey);
+tree_hash_ssz_encoding_as_vector!(SecretKey);
 
 #[cfg(test)]
 mod tests {
diff --git a/eth2/utils/bls/src/signature.rs b/eth2/utils/bls/src/signature.rs
index cf6c8fe5a..3fb68dc53 100644
--- a/eth2/utils/bls/src/signature.rs
+++ b/eth2/utils/bls/src/signature.rs
@@ -5,7 +5,7 @@ use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::HexVisitor;
 use ssz::{decode, ssz_encode, Decodable, DecodeError, Encodable, SszStream};
-use tree_hash::impl_tree_hash_for_ssz_bytes;
+use tree_hash::tree_hash_ssz_encoding_as_vector;
 
 /// A single BLS signature.
 ///
@@ -115,7 +115,7 @@ impl Decodable for Signature {
     }
 }
 
-impl_tree_hash_for_ssz_bytes!(Signature);
+tree_hash_ssz_encoding_as_vector!(Signature);
 
 impl Serialize for Signature {
     /// Serde serialization is compliant the Ethereum YAML test format.
diff --git a/eth2/utils/boolean-bitfield/src/lib.rs b/eth2/utils/boolean-bitfield/src/lib.rs
index fbd0e2ecd..d35d87c5c 100644
--- a/eth2/utils/boolean-bitfield/src/lib.rs
+++ b/eth2/utils/boolean-bitfield/src/lib.rs
@@ -9,7 +9,7 @@ use serde_hex::{encode, PrefixedHexVisitor};
 use ssz::{Decodable, Encodable};
 use std::cmp;
 use std::default;
-use tree_hash::impl_tree_hash_for_ssz_bytes;
+use tree_hash::tree_hash_ssz_encoding_as_list;
 
 /// A BooleanBitfield represents a set of booleans compactly stored as a vector of bits.
 /// The BooleanBitfield is given a fixed size during construction. Reads outside of the current size return an out-of-bounds error. Writes outside of the current size expand the size of the set.
@@ -257,7 +257,7 @@ impl<'de> Deserialize<'de> for BooleanBitfield {
     }
 }
 
-impl_tree_hash_for_ssz_bytes!(BooleanBitfield);
+tree_hash_ssz_encoding_as_list!(BooleanBitfield);
 
 #[cfg(test)]
 mod tests {
diff --git a/eth2/utils/tree_hash/src/lib.rs b/eth2/utils/tree_hash/src/lib.rs
index fd1708a2d..ed60079c8 100644
--- a/eth2/utils/tree_hash/src/lib.rs
+++ b/eth2/utils/tree_hash/src/lib.rs
@@ -28,7 +28,7 @@ fn num_nodes(num_leaves: usize) -> usize {
 }
 
 #[macro_export]
-macro_rules! impl_tree_hash_for_ssz_bytes {
+macro_rules! tree_hash_ssz_encoding_as_vector {
     ($type: ident) => {
         impl tree_hash::TreeHash for $type {
             fn tree_hash_type() -> tree_hash::TreeHashType {
@@ -49,3 +49,25 @@ macro_rules! impl_tree_hash_for_ssz_bytes {
         }
     };
 }
+#[macro_export]
+macro_rules! tree_hash_ssz_encoding_as_list {
+    ($type: ident) => {
+        impl tree_hash::TreeHash for $type {
+            fn tree_hash_type() -> tree_hash::TreeHashType {
+                tree_hash::TreeHashType::List
+            }
+
+            fn tree_hash_packed_encoding(&self) -> Vec<u8> {
+                unreachable!("List should never be packed.")
+            }
+
+            fn tree_hash_packing_factor() -> usize {
+                unreachable!("List should never be packed.")
+            }
+
+            fn tree_hash_root(&self) -> Vec<u8> {
+                ssz::ssz_encode(self).tree_hash_root()
+            }
+        }
+    };
+}