diff --git a/benches/bank.rs b/benches/bank.rs
index 1583aee6f..eb2ece6b4 100644
--- a/benches/bank.rs
+++ b/benches/bank.rs
@@ -1,8 +1,8 @@
 #![feature(test)]
-extern crate bincode;
-extern crate rayon;
-extern crate solana;
-extern crate solana_sdk;
+
+
+
+
 extern crate test;
 
 use solana::bank::*;
diff --git a/benches/banking_stage.rs b/benches/banking_stage.rs
index 26cf54692..05254651d 100644
--- a/benches/banking_stage.rs
+++ b/benches/banking_stage.rs
@@ -1,9 +1,9 @@
 #![feature(test)]
-extern crate bincode;
-extern crate rand;
-extern crate rayon;
-extern crate solana;
-extern crate solana_sdk;
+
+
+
+
+
 extern crate test;
 
 use rand::{thread_rng, Rng};
diff --git a/benches/db_ledger.rs b/benches/db_ledger.rs
index 1782100fb..7ee931652 100644
--- a/benches/db_ledger.rs
+++ b/benches/db_ledger.rs
@@ -1,7 +1,7 @@
 #![feature(test)]
-extern crate rand;
-extern crate rocksdb;
-extern crate solana;
+use rand;
+
+
 extern crate test;
 
 use rand::seq::SliceRandom;
diff --git a/benches/ledger.rs b/benches/ledger.rs
index 8bfa8f19c..84e4b5941 100644
--- a/benches/ledger.rs
+++ b/benches/ledger.rs
@@ -1,6 +1,6 @@
 #![feature(test)]
-extern crate solana;
-extern crate solana_sdk;
+
+
 extern crate test;
 
 use solana::entry::reconstruct_entries_from_blobs;
diff --git a/benches/signature.rs b/benches/signature.rs
index 21d50daab..0916bb49c 100644
--- a/benches/signature.rs
+++ b/benches/signature.rs
@@ -1,6 +1,6 @@
 #![feature(test)]
-extern crate solana;
-extern crate solana_sdk;
+
+
 extern crate test;
 
 use solana::signature::GenKeys;
diff --git a/benches/sigverify.rs b/benches/sigverify.rs
index 5601bcbd0..d4fc446f3 100644
--- a/benches/sigverify.rs
+++ b/benches/sigverify.rs
@@ -1,7 +1,7 @@
 #![feature(test)]
-extern crate bincode;
-extern crate rayon;
-extern crate solana;
+
+
+
 extern crate test;
 
 use solana::packet::to_packets;
diff --git a/src/bin/bench-streamer.rs b/src/bin/bench-streamer.rs
index e1d127dec..a5732e780 100644
--- a/src/bin/bench-streamer.rs
+++ b/src/bin/bench-streamer.rs
@@ -1,5 +1,5 @@
-extern crate clap;
-extern crate solana;
+
+
 
 use clap::{App, Arg};
 use solana::netutil::bind_to;
diff --git a/src/bin/bench-tps.rs b/src/bin/bench-tps.rs
index c8fcb8335..62d02f782 100644
--- a/src/bin/bench-tps.rs
+++ b/src/bin/bench-tps.rs
@@ -1,11 +1,11 @@
 #[macro_use]
 extern crate clap;
-extern crate rayon;
+
 #[macro_use]
 extern crate solana;
-extern crate solana_drone;
-extern crate solana_metrics;
-extern crate solana_sdk;
+
+use solana_metrics;
+
 
 use clap::{App, Arg};
 
diff --git a/src/bin/fullnode-config.rs b/src/bin/fullnode-config.rs
index 3433094b0..4721d117e 100644
--- a/src/bin/fullnode-config.rs
+++ b/src/bin/fullnode-config.rs
@@ -1,10 +1,10 @@
 #[macro_use]
 extern crate clap;
-extern crate dirs;
-extern crate ring;
-extern crate serde_json;
-extern crate solana;
-extern crate solana_sdk;
+use dirs;
+
+use serde_json;
+
+
 
 use clap::{App, Arg};
 use ring::rand::SystemRandom;
diff --git a/src/bin/fullnode.rs b/src/bin/fullnode.rs
index 00d440dd4..e9e9bb5cd 100644
--- a/src/bin/fullnode.rs
+++ b/src/bin/fullnode.rs
@@ -1,13 +1,13 @@
 #[macro_use]
 extern crate clap;
-extern crate getopts;
+
 #[macro_use]
 extern crate log;
-extern crate serde_json;
+use serde_json;
 #[macro_use]
 extern crate solana;
-extern crate solana_metrics;
-extern crate solana_sdk;
+use solana_metrics;
+
 
 use clap::{App, Arg};
 use solana::client::mk_client;
diff --git a/src/bin/genesis.rs b/src/bin/genesis.rs
index 8da12c3de..9f877d12e 100644
--- a/src/bin/genesis.rs
+++ b/src/bin/genesis.rs
@@ -1,12 +1,12 @@
 //! A command-line executable for generating the chain's genesis block.
 
-extern crate atty;
+
 #[macro_use]
 extern crate clap;
-extern crate serde_json;
-extern crate solana;
-extern crate solana_sdk;
-extern crate untrusted;
+use serde_json;
+
+
+
 
 use clap::{App, Arg};
 use solana::ledger::LedgerWriter;
@@ -23,7 +23,7 @@ use std::path::Path;
  */
 pub const BOOTSTRAP_LEADER_TOKENS: u64 = 2;
 
-fn main() -> Result<(), Box<error::Error>> {
+fn main() -> Result<(), Box<dyn error::Error>> {
     let matches = App::new("solana-genesis")
         .version(crate_version!())
         .arg(
diff --git a/src/bin/keygen.rs b/src/bin/keygen.rs
index a914a6a38..2e42db56f 100644
--- a/src/bin/keygen.rs
+++ b/src/bin/keygen.rs
@@ -1,15 +1,15 @@
 #[macro_use]
 extern crate clap;
-extern crate dirs;
-extern crate ring;
-extern crate serde_json;
-extern crate solana;
+use dirs;
+
+
+
 
 use clap::{App, Arg};
 use solana::wallet::gen_keypair_file;
 use std::error;
 
-fn main() -> Result<(), Box<error::Error>> {
+fn main() -> Result<(), Box<dyn error::Error>> {
     let matches = App::new("solana-keygen")
         .version(crate_version!())
         .arg(
diff --git a/src/bin/ledger-tool.rs b/src/bin/ledger-tool.rs
index 44fc7e92c..0081a9429 100644
--- a/src/bin/ledger-tool.rs
+++ b/src/bin/ledger-tool.rs
@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate clap;
-extern crate serde_json;
-extern crate solana;
+use serde_json;
+
 
 use clap::{App, Arg, SubCommand};
 use solana::bank::Bank;
diff --git a/src/bin/replicator.rs b/src/bin/replicator.rs
index fd28ad936..cdc8a8103 100644
--- a/src/bin/replicator.rs
+++ b/src/bin/replicator.rs
@@ -1,11 +1,11 @@
 #[macro_use]
 extern crate clap;
-extern crate getopts;
-extern crate serde_json;
+
+use serde_json;
 #[macro_use]
 extern crate solana;
-extern crate solana_drone;
-extern crate solana_sdk;
+
+
 
 use clap::{App, Arg};
 use solana::cluster_info::{Node, NodeInfo};
diff --git a/src/bin/upload-perf.rs b/src/bin/upload-perf.rs
index 7548a9c61..7a0d353a1 100644
--- a/src/bin/upload-perf.rs
+++ b/src/bin/upload-perf.rs
@@ -1,6 +1,6 @@
-extern crate serde_json;
-extern crate solana;
-extern crate solana_metrics;
+use serde_json;
+
+use solana_metrics;
 
 use serde_json::Value;
 use solana_metrics::influxdb;
diff --git a/src/bin/wallet.rs b/src/bin/wallet.rs
index 0694e1f9d..091c8b9ef 100644
--- a/src/bin/wallet.rs
+++ b/src/bin/wallet.rs
@@ -1,9 +1,9 @@
 #[macro_use]
 extern crate clap;
-extern crate dirs;
+use dirs;
 #[macro_use]
 extern crate solana;
-extern crate solana_sdk;
+
 
 use clap::{App, Arg, ArgMatches, SubCommand};
 use solana::logger;
@@ -12,7 +12,7 @@ use solana_sdk::signature::{read_keypair, KeypairUtil};
 use std::error;
 use std::net::SocketAddr;
 
-pub fn parse_args(matches: &ArgMatches) -> Result<WalletConfig, Box<error::Error>> {
+pub fn parse_args(matches: &ArgMatches<'_>) -> Result<WalletConfig, Box<dyn error::Error>> {
     let network = if let Some(addr) = matches.value_of("network") {
         addr.parse().or_else(|_| {
             Err(WalletError::BadParameter(
@@ -61,7 +61,7 @@ pub fn parse_args(matches: &ArgMatches) -> Result<WalletConfig, Box<error::Error
     })
 }
 
-fn main() -> Result<(), Box<error::Error>> {
+fn main() -> Result<(), Box<dyn error::Error>> {
     logger::setup();
     let matches = App::new("solana-wallet")
         .version(crate_version!())
diff --git a/src/broadcast_service.rs b/src/broadcast_service.rs
index 779e4606e..a639c9961 100644
--- a/src/broadcast_service.rs
+++ b/src/broadcast_service.rs
@@ -83,7 +83,7 @@ fn broadcast(
     let chunking_elapsed = duration_as_ms(&blobs_chunking.elapsed());
 
     let broadcast_start = Instant::now();
-    for mut blobs in blobs_chunked {
+    for blobs in blobs_chunked {
         let blobs_len = blobs.len();
         trace!("{}: broadcast blobs.len: {}", id, blobs_len);
 
diff --git a/src/crds_gossip.rs b/src/crds_gossip.rs
index 30f2363ce..36384d47b 100644
--- a/src/crds_gossip.rs
+++ b/src/crds_gossip.rs
@@ -401,7 +401,7 @@ mod test {
         let network_values: Vec<Node> = network.values().cloned().collect();
         for t in start..end {
             let now = t as u64 * 100;
-            let mut requests: Vec<_> = {
+            let requests: Vec<_> = {
                 network_values
                     .par_iter()
                     .filter_map(|from| from.lock().unwrap().new_pull_request(now).ok())
diff --git a/src/crds_gossip_push.rs b/src/crds_gossip_push.rs
index d56e78921..615d1d80c 100644
--- a/src/crds_gossip_push.rs
+++ b/src/crds_gossip_push.rs
@@ -189,7 +189,7 @@ impl CrdsGossipPush {
                 }
             }
             let size = cmp::max(CRDS_GOSSIP_BLOOM_SIZE, network_size);
-            let mut bloom = Bloom::random(size, 0.1, 1024 * 8 * 4);
+            let bloom = Bloom::random(size, 0.1, 1024 * 8 * 4);
             new_items.insert(val.0.pubkey(), bloom);
             if new_items.len() == need {
                 break;
diff --git a/src/crds_value.rs b/src/crds_value.rs
index cd170656a..2fcd97a59 100644
--- a/src/crds_value.rs
+++ b/src/crds_value.rs
@@ -101,7 +101,7 @@ pub enum CrdsValueLabel {
 }
 
 impl fmt::Display for CrdsValueLabel {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             CrdsValueLabel::ContactInfo(_) => write!(f, "ContactInfo({})", self.pubkey()),
             CrdsValueLabel::Vote(_) => write!(f, "Vote({})", self.pubkey()),
diff --git a/src/db_window.rs b/src/db_window.rs
index 79f38e703..e8bdeed6a 100644
--- a/src/db_window.rs
+++ b/src/db_window.rs
@@ -125,8 +125,8 @@ pub fn find_missing_indexes(
     slot: u64,
     start_index: u64,
     end_index: u64,
-    key: &Fn(u64, u64) -> Vec<u8>,
-    index_from_key: &Fn(&[u8]) -> Result<u64>,
+    key: &dyn Fn(u64, u64) -> Vec<u8>,
+    index_from_key: &dyn Fn(&[u8]) -> Result<u64>,
     max_missing: usize,
 ) -> Vec<u64> {
     if start_index >= end_index || max_missing == 0 {
@@ -458,7 +458,7 @@ mod test {
             let t_responder = responder("streamer_send_test", Arc::new(send), r_responder);
             let mut msgs = Vec::new();
             for i in 0..10 {
-                let mut b = SharedBlob::default();
+                let b = SharedBlob::default();
                 {
                     let mut w = b.write().unwrap();
                     w.data[0] = i as u8;
diff --git a/src/erasure.rs b/src/erasure.rs
index 2ee02d600..c504bffdd 100644
--- a/src/erasure.rs
+++ b/src/erasure.rs
@@ -96,7 +96,7 @@ pub fn generate_coding_blocks(coding: &mut [&mut [u8]], data: &[&[u8]]) -> Resul
         data_arg.push(block.as_ptr());
     }
     let mut coding_arg = Vec::with_capacity(coding.len());
-    for mut block in coding {
+    for block in coding {
         if block_len != block.len() as i32 {
             error!(
                 "coding block size incorrect {} expected {}",
diff --git a/src/lib.rs b/src/lib.rs
index 36ef9ebb0..06aaf8dbc 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -74,59 +74,59 @@ pub mod vote_stage;
 pub mod wallet;
 pub mod window;
 pub mod window_service;
-extern crate bincode;
-extern crate bs58;
-extern crate bv;
-extern crate byteorder;
-extern crate bytes;
-extern crate chrono;
-extern crate clap;
-extern crate dirs;
-extern crate elf;
-extern crate generic_array;
+use bincode;
+use bs58;
+
+
+
+
+
+
+use elf;
+
 #[cfg(test)]
 #[cfg(any(feature = "chacha", feature = "cuda"))]
 #[macro_use]
 extern crate hex_literal;
-extern crate indexmap;
-extern crate ipnetwork;
-extern crate itertools;
-extern crate libc;
+
+
+
+
 #[macro_use]
 extern crate log;
-extern crate nix;
-extern crate pnet_datalink;
-extern crate rayon;
-extern crate reqwest;
-extern crate ring;
-extern crate rocksdb;
-extern crate serde;
+
+use pnet_datalink;
+
+use reqwest;
+
+use rocksdb;
+
 #[macro_use]
 extern crate serde_derive;
 #[macro_use]
 extern crate serde_json;
-extern crate serde_cbor;
-extern crate sha2;
-extern crate socket2;
-extern crate solana_drone;
-extern crate solana_jsonrpc_core as jsonrpc_core;
-extern crate solana_jsonrpc_http_server as jsonrpc_http_server;
-extern crate solana_system_program;
+
+
+
+
+use solana_jsonrpc_core as jsonrpc_core;
+use solana_jsonrpc_http_server as jsonrpc_http_server;
+use solana_system_program;
 #[macro_use]
 extern crate solana_jsonrpc_macros as jsonrpc_macros;
-extern crate solana_jsonrpc_pubsub as jsonrpc_pubsub;
-extern crate solana_jsonrpc_ws_server as jsonrpc_ws_server;
-extern crate solana_metrics;
-extern crate solana_native_loader;
-extern crate solana_sdk;
-extern crate sys_info;
-extern crate tokio;
-extern crate tokio_codec;
-extern crate untrusted;
+use solana_jsonrpc_pubsub as jsonrpc_pubsub;
+use solana_jsonrpc_ws_server as jsonrpc_ws_server;
+use solana_metrics;
+use solana_native_loader;
+
+
+
+
+use untrusted;
 
 #[cfg(test)]
 #[macro_use]
 extern crate matches;
 
-extern crate rand;
-extern crate rand_chacha;
+use rand;
+
diff --git a/src/logger.rs b/src/logger.rs
index 08375adf5..5948f9fdf 100644
--- a/src/logger.rs
+++ b/src/logger.rs
@@ -2,7 +2,7 @@
 //! `setup()` may be called multiple times.
 
 use std::sync::{Once, ONCE_INIT};
-extern crate env_logger;
+use env_logger;
 
 static INIT: Once = ONCE_INIT;
 
diff --git a/src/packet.rs b/src/packet.rs
index 506c06fa4..311236ae8 100644
--- a/src/packet.rs
+++ b/src/packet.rs
@@ -49,7 +49,7 @@ pub struct Packet {
 }
 
 impl fmt::Debug for Packet {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             f,
             "Packet {{ size: {:?}, addr: {:?} }}",
@@ -135,7 +135,7 @@ impl PartialEq for Blob {
 }
 
 impl fmt::Debug for Blob {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             f,
             "Blob {{ size: {:?}, addr: {:?} }}",
@@ -217,7 +217,7 @@ impl Packets {
 pub fn to_packets_chunked<T: Serialize>(xs: &[T], chunks: usize) -> Vec<SharedPackets> {
     let mut out = vec![];
     for x in xs.chunks(chunks) {
-        let mut p = SharedPackets::default();
+        let p = SharedPackets::default();
         p.write()
             .unwrap()
             .packets
diff --git a/src/result.rs b/src/result.rs
index 458c3880e..b3a319992 100644
--- a/src/result.rs
+++ b/src/result.rs
@@ -19,7 +19,7 @@ pub enum Error {
     IO(std::io::Error),
     JSON(serde_json::Error),
     AddrParse(std::net::AddrParseError),
-    JoinError(Box<Any + Send + 'static>),
+    JoinError(Box<dyn Any + Send + 'static>),
     RecvError(std::sync::mpsc::RecvError),
     RecvTimeoutError(std::sync::mpsc::RecvTimeoutError),
     Serialize(std::boxed::Box<bincode::ErrorKind>),
@@ -38,7 +38,7 @@ pub enum Error {
 pub type Result<T> = std::result::Result<T, Error>;
 
 impl std::fmt::Display for Error {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "solana error")
     }
 }
@@ -76,8 +76,8 @@ impl<T> std::convert::From<std::sync::mpsc::SendError<T>> for Error {
         Error::SendError
     }
 }
-impl std::convert::From<Box<Any + Send + 'static>> for Error {
-    fn from(e: Box<Any + Send + 'static>) -> Error {
+impl std::convert::From<Box<dyn Any + Send + 'static>> for Error {
+    fn from(e: Box<dyn Any + Send + 'static>) -> Error {
         Error::JoinError(e)
     }
 }
diff --git a/src/rpc_request.rs b/src/rpc_request.rs
index 30c926836..0621c6200 100644
--- a/src/rpc_request.rs
+++ b/src/rpc_request.rs
@@ -62,7 +62,7 @@ impl RpcRequest {
         client: &RpcClient,
         id: u64,
         params: Option<Value>,
-    ) -> Result<Value, Box<error::Error>> {
+    ) -> Result<Value, Box<dyn error::Error>> {
         let request = self.build_request_json(id, params);
 
         let mut response = client
@@ -116,7 +116,7 @@ pub enum RpcError {
 }
 
 impl fmt::Display for RpcError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "invalid")
     }
 }
@@ -126,7 +126,7 @@ impl error::Error for RpcError {
         "invalid"
     }
 
-    fn cause(&self) -> Option<&error::Error> {
+    fn cause(&self) -> Option<&dyn error::Error> {
         // Generic error, underlying cause isn't tracked.
         None
     }
diff --git a/src/sigverify.rs b/src/sigverify.rs
index 20b275703..d8ec30f72 100644
--- a/src/sigverify.rs
+++ b/src/sigverify.rs
@@ -294,7 +294,7 @@ pub fn ed25519_verify(batches: &[SharedPackets]) -> Vec<Vec<u8>> {
     trace!("done verify");
     let mut num = 0;
     for (vs, sig_vs) in rvs.iter_mut().zip(sig_lens.iter()) {
-        for (mut v, sig_v) in vs.iter_mut().zip(sig_vs.iter()) {
+        for (v, sig_v) in vs.iter_mut().zip(sig_vs.iter()) {
             let mut vout = 1;
             for _ in 0..*sig_v {
                 if 0 == out[num] {
diff --git a/src/streamer.rs b/src/streamer.rs
index 9a67069bb..9d3ce3c82 100644
--- a/src/streamer.rs
+++ b/src/streamer.rs
@@ -179,7 +179,7 @@ mod test {
             let t_responder = responder("streamer_send_test", Arc::new(send), r_responder);
             let mut msgs = Vec::new();
             for i in 0..10 {
-                let mut b = SharedBlob::default();
+                let b = SharedBlob::default();
                 {
                     let mut w = b.write().unwrap();
                     w.data[0] = i as u8;
diff --git a/src/tvu.rs b/src/tvu.rs
index 8d98af78f..60d267129 100644
--- a/src/tvu.rs
+++ b/src/tvu.rs
@@ -313,7 +313,7 @@ pub mod tests {
             alice_ref_balance -= transfer_amount;
 
             for entry in vec![entry0, entry_tick0, entry_tick1, entry1, entry_tick2] {
-                let mut b = SharedBlob::default();
+                let b = SharedBlob::default();
                 {
                     let mut w = b.write().unwrap();
                     w.set_index(blob_idx).unwrap();
diff --git a/src/wallet.rs b/src/wallet.rs
index 63f267fd0..64a0f0f8b 100644
--- a/src/wallet.rs
+++ b/src/wallet.rs
@@ -65,7 +65,7 @@ pub enum WalletError {
 }
 
 impl fmt::Display for WalletError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "invalid")
     }
 }
@@ -75,7 +75,7 @@ impl error::Error for WalletError {
         "invalid"
     }
 
-    fn cause(&self) -> Option<&error::Error> {
+    fn cause(&self) -> Option<&dyn error::Error> {
         // Generic error, underlying cause isn't tracked.
         None
     }
@@ -119,8 +119,8 @@ impl WalletConfig {
 
 pub fn parse_command(
     pubkey: Pubkey,
-    matches: &ArgMatches,
-) -> Result<WalletCommand, Box<error::Error>> {
+    matches: &ArgMatches<'_>,
+) -> Result<WalletCommand, Box<dyn error::Error>> {
     let response = match matches.subcommand() {
         ("address", Some(_address_matches)) => Ok(WalletCommand::Address),
         ("airdrop", Some(airdrop_matches)) => {
@@ -308,7 +308,7 @@ pub fn parse_command(
     Ok(response)
 }
 
-pub fn process_command(config: &WalletConfig) -> Result<String, Box<error::Error>> {
+pub fn process_command(config: &WalletConfig) -> Result<String, Box<dyn error::Error>> {
     if let WalletCommand::Address = config.command {
         // Get address of this client
         return Ok(format!("{}", config.id.pubkey()));
@@ -667,7 +667,7 @@ pub fn read_leader(path: &str) -> Result<Config, WalletError> {
     })
 }
 
-pub fn gen_keypair_file(outfile: String) -> Result<String, Box<error::Error>> {
+pub fn gen_keypair_file(outfile: String) -> Result<String, Box<dyn error::Error>> {
     let rnd = SystemRandom::new();
     let pkcs8_bytes = Ed25519KeyPair::generate_pkcs8(&rnd)?;
     let serialized = serde_json::to_string(&pkcs8_bytes.to_vec())?;
@@ -682,7 +682,7 @@ pub fn gen_keypair_file(outfile: String) -> Result<String, Box<error::Error>> {
     Ok(serialized)
 }
 
-fn get_last_id(rpc_client: &RpcClient) -> Result<Hash, Box<error::Error>> {
+fn get_last_id(rpc_client: &RpcClient) -> Result<Hash, Box<dyn error::Error>> {
     let result = RpcRequest::GetLastId.make_rpc_request(rpc_client, 1, None)?;
     if result.as_str().is_none() {
         Err(WalletError::RpcRequestError(
@@ -696,7 +696,7 @@ fn get_last_id(rpc_client: &RpcClient) -> Result<Hash, Box<error::Error>> {
     Ok(Hash::new(&last_id_vec))
 }
 
-fn send_tx(rpc_client: &RpcClient, tx: &Transaction) -> Result<String, Box<error::Error>> {
+fn send_tx(rpc_client: &RpcClient, tx: &Transaction) -> Result<String, Box<dyn error::Error>> {
     let serialized = serialize(tx).unwrap();
     let params = json!([serialized]);
     let signature = RpcRequest::SendTransaction.make_rpc_request(rpc_client, 2, Some(params))?;
@@ -711,7 +711,7 @@ fn send_tx(rpc_client: &RpcClient, tx: &Transaction) -> Result<String, Box<error
 fn confirm_tx(
     rpc_client: &RpcClient,
     signature: &str,
-) -> Result<RpcSignatureStatus, Box<error::Error>> {
+) -> Result<RpcSignatureStatus, Box<dyn error::Error>> {
     let params = json!([signature.to_string()]);
     let signature_status =
         RpcRequest::GetSignatureStatus.make_rpc_request(rpc_client, 1, Some(params))?;
@@ -727,7 +727,7 @@ fn confirm_tx(
     }
 }
 
-fn send_and_confirm_tx(rpc_client: &RpcClient, tx: &Transaction) -> Result<(), Box<error::Error>> {
+fn send_and_confirm_tx(rpc_client: &RpcClient, tx: &Transaction) -> Result<(), Box<dyn error::Error>> {
     let mut send_retries = 3;
     while send_retries > 0 {
         let mut status_retries = 4;
diff --git a/src/window.rs b/src/window.rs
index 8edf52cf3..68f29d197 100644
--- a/src/window.rs
+++ b/src/window.rs
@@ -448,7 +448,7 @@ mod test {
             let t_responder = responder("streamer_send_test", Arc::new(send), r_responder);
             let mut msgs = Vec::new();
             for i in 0..10 {
-                let mut b = SharedBlob::default();
+                let b = SharedBlob::default();
                 {
                     let mut w = b.write().unwrap();
                     w.data[0] = i as u8;
diff --git a/src/window_service.rs b/src/window_service.rs
index 1137fcad8..ff2a678cb 100644
--- a/src/window_service.rs
+++ b/src/window_service.rs
@@ -298,7 +298,7 @@ mod test {
                 tn.sockets.replicate.into_iter().map(Arc::new).collect();
 
             let t_responder = responder("window_send_test", blob_sockets[0].clone(), r_responder);
-            let mut num_blobs_to_make = 10;
+            let num_blobs_to_make = 10;
             let gossip_address = &tn.info.gossip;
             let msgs = make_consecutive_blobs(
                 me_id,
diff --git a/tests/data_replicator.rs b/tests/data_replicator.rs
index 4fab4219f..079519e7a 100644
--- a/tests/data_replicator.rs
+++ b/tests/data_replicator.rs
@@ -1,8 +1,8 @@
 #[macro_use]
 extern crate log;
-extern crate rayon;
-extern crate solana;
-extern crate solana_sdk;
+
+
+
 
 use rayon::iter::*;
 use solana::cluster_info::{ClusterInfo, Node};
diff --git a/tests/multinode.rs b/tests/multinode.rs
index e86c6cfb4..e9f4a3fc0 100644
--- a/tests/multinode.rs
+++ b/tests/multinode.rs
@@ -1,10 +1,10 @@
 #[macro_use]
 extern crate log;
-extern crate bincode;
-extern crate chrono;
-extern crate serde_json;
-extern crate solana;
-extern crate solana_sdk;
+
+
+
+use solana;
+
 
 use solana::blob_fetch_stage::BlobFetchStage;
 use solana::cluster_info::{ClusterInfo, Node, NodeInfo};
@@ -272,7 +272,7 @@ fn test_multi_node_validator_catchup_from_zero() -> result::Result<()> {
                 .unwrap();
         info!("validator balance {}", validator_balance);
 
-        let mut val = Fullnode::new(
+        let val = Fullnode::new(
             validator,
             &ledger_path,
             keypair,
@@ -871,7 +871,7 @@ fn test_leader_to_validator_transition() {
     let mut converged = false;
     for _ in 0..30 {
         let num = spy_node.read().unwrap().convergence();
-        let mut v: Vec<NodeInfo> = spy_node.read().unwrap().rpc_peers();
+        let v: Vec<NodeInfo> = spy_node.read().unwrap().rpc_peers();
         // There's only one person excluding the spy node (the leader) who should see
         // two nodes on the network
         if num >= 2 && v.len() >= 1 {
@@ -1605,7 +1605,7 @@ fn test_broadcast_last_tick() {
     // Check that the nodes got the last broadcasted blob
     for (_, receiver) in blob_fetch_stages.iter() {
         let mut last_tick_blob: SharedBlob = SharedBlob::default();
-        while let Ok(mut new_blobs) = receiver.try_recv() {
+        while let Ok(new_blobs) = receiver.try_recv() {
             let last_blob = new_blobs.into_iter().find(|b| {
                 b.read().unwrap().index().expect("Expected index in blob")
                     == last_tick_entry_height - 1
diff --git a/tests/programs.rs b/tests/programs.rs
index d5c1776f0..20f4fe1b2 100644
--- a/tests/programs.rs
+++ b/tests/programs.rs
@@ -1,9 +1,9 @@
-extern crate bincode;
-extern crate elf;
-extern crate serde_derive;
-extern crate solana;
-extern crate solana_native_loader;
-extern crate solana_sdk;
+
+
+
+use solana;
+use solana_native_loader;
+
 
 use solana::bank::Bank;
 use solana::logger;
diff --git a/tests/replicator.rs b/tests/replicator.rs
index beed577de..ae3779326 100644
--- a/tests/replicator.rs
+++ b/tests/replicator.rs
@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate log;
-extern crate solana;
-extern crate solana_sdk;
+
+
 
 use solana::client::mk_client;
 use solana::cluster_info::{Node, NodeInfo};