diff --git a/ci/buildkite.yml b/ci/buildkite.yml
index f196f6dca8..a9bca64a19 100644
--- a/ci/buildkite.yml
+++ b/ci/buildkite.yml
@@ -14,7 +14,7 @@ steps:
       - "queue=cuda"
   - command: "ci/test-bench.sh"
     name: "bench"
-    timeout_in_minutes: 20
+    timeout_in_minutes: 40
   - command: ". ci/rust-version.sh; ci/docker-run.sh $$rust_stable_docker_image ci/test-stable.sh"
     name: "stable"
     timeout_in_minutes: 30
diff --git a/ci/rust-version.sh b/ci/rust-version.sh
index 4a40f94f04..8997909c33 100644
--- a/ci/rust-version.sh
+++ b/ci/rust-version.sh
@@ -16,8 +16,8 @@
 export rust_stable=1.34.0
 export rust_stable_docker_image=solanalabs/rust:1.34.0
 
-export rust_nightly=nightly-2019-03-14
-export rust_nightly_docker_image=solanalabs/rust-nightly:2019-03-14
+export rust_nightly=nightly-2019-05-01
+export rust_nightly_docker_image=solanalabs/rust-nightly:2019-05-01
 
 [[ -z $1 ]] || (
 
diff --git a/core/src/fullnode.rs b/core/src/fullnode.rs
index 4e6363140a..38aec6d266 100644
--- a/core/src/fullnode.rs
+++ b/core/src/fullnode.rs
@@ -390,7 +390,6 @@ pub fn make_active_set_entries(
 
 pub fn new_fullnode_for_tests() -> (Fullnode, ContactInfo, Keypair, String) {
     use crate::blocktree::create_new_tmp_ledger;
-    use crate::cluster_info::Node;
 
     let node_keypair = Arc::new(Keypair::new());
     let node = Node::new_localhost_with_pubkey(&node_keypair.pubkey());
diff --git a/core/src/sigverify.rs b/core/src/sigverify.rs
index e7f161e9b5..59a77d0295 100644
--- a/core/src/sigverify.rs
+++ b/core/src/sigverify.rs
@@ -68,9 +68,6 @@ pub fn init() {
 }
 
 fn verify_packet(packet: &Packet) -> u8 {
-    use solana_sdk::pubkey::Pubkey;
-    use solana_sdk::signature::Signature;
-
     let (sig_len, sig_start, msg_start, pubkey_start) = get_packet_offsets(packet, 0);
     let mut sig_start = sig_start as usize;
     let mut pubkey_start = pubkey_start as usize;
diff --git a/kvstore/src/io_utils.rs b/kvstore/src/io_utils.rs
index 0c59cdd18f..5082925c8b 100644
--- a/kvstore/src/io_utils.rs
+++ b/kvstore/src/io_utils.rs
@@ -244,8 +244,6 @@ where
 
 impl Write for SharedWriter {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
-        use std::cmp;
-
         let mut vec = self.buf.write().expect(BACKING_ERR);
 
         // Calc ranges
diff --git a/runtime/src/bank.rs b/runtime/src/bank.rs
index 000cb530e8..590889edfd 100644
--- a/runtime/src/bank.rs
+++ b/runtime/src/bank.rs
@@ -1324,7 +1324,8 @@ mod tests {
         // send a bogus instruction to system_program, cause an instruction error
         tx.message.instructions[0].data[0] = 40;
 
-        bank.process_transaction(&tx).is_err(); // fails with an instruction error
+        bank.process_transaction(&tx)
+            .expect_err("instruction error"); // fails with an instruction error
         assert_eq!(bank.get_balance(&leader), initial_balance + 5); // gots our bucks
         assert_eq!(bank.get_balance(&key2.pubkey()), 1); //  our fee ------V
         assert_eq!(bank.get_balance(&mint_keypair.pubkey()), 100 - 5 - 3 - 1);