diff --git a/beacon_chain/utils/ssz/src/encode.rs b/beacon_chain/utils/ssz/src/encode.rs
index 5080924cc..b501ebe40 100644
--- a/beacon_chain/utils/ssz/src/encode.rs
+++ b/beacon_chain/utils/ssz/src/encode.rs
@@ -41,7 +41,7 @@ impl SszStream {
     ///
     /// The length of the supplied bytes will be concatenated
     /// to the stream before the supplied bytes.
-    pub fn append_encoded_val(&mut self, vec: &Vec<u8>) {
+    pub fn append_encoded_val(&mut self, vec: &[u8]) {
         self.buffer.extend_from_slice(
             &encode_length(vec.len(),
             LENGTH_BYTES));
@@ -51,7 +51,7 @@ impl SszStream {
     /// Append some ssz encoded bytes to the stream without calculating length
     ///
     /// The raw bytes will be concatenated to the stream.
-    pub fn append_encoded_raw(&mut self, vec: &Vec<u8>) {
+    pub fn append_encoded_raw(&mut self, vec: &[u8]) {
         self.buffer.extend_from_slice(&vec);
     }
 
@@ -59,7 +59,7 @@ impl SszStream {
     ///
     /// The length of the list will be concatenated to the stream, then
     /// each item in the vector will be encoded and concatenated.
-    pub fn append_vec<E>(&mut self, vec: &Vec<E>)
+    pub fn append_vec<E>(&mut self, vec: &[E])
         where E: Encodable
     {
         let mut list_stream = SszStream::new();
diff --git a/beacon_chain/utils/ssz/src/impl_encode.rs b/beacon_chain/utils/ssz/src/impl_encode.rs
index 36776e071..a2e955d37 100644
--- a/beacon_chain/utils/ssz/src/impl_encode.rs
+++ b/beacon_chain/utils/ssz/src/impl_encode.rs
@@ -1,3 +1,5 @@
+#![cfg_attr(not(feature = "clippy"), allow(cast_lossless))]
+
 extern crate bytes;
 
 use super::{