diff --git a/Cargo.lock b/Cargo.lock
index b21fb1d63..b69736c2e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -192,13 +192,13 @@ dependencies = [
  "ethcore 0.9.99",
  "ethcore-util 0.9.99",
  "ethsync 0.9.99",
- "jsonrpc-core 1.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "jsonrpc-core 1.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "jsonrpc-http-server 1.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 0.6.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_codegen 0.6.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "syntex 0.28.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syntex 0.29.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "target_info 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -346,13 +346,13 @@ dependencies = [
 
 [[package]]
 name = "jsonrpc-core"
-version = "1.1.3"
+version = "1.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "serde 0.6.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_codegen 0.6.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "syntex 0.28.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syntex 0.29.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -361,7 +361,7 @@ version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "hyper 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "jsonrpc-core 1.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "jsonrpc-core 1.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -661,14 +661,6 @@ name = "strsim"
 version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "syntex"
-version = "0.28.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "syntex_syntax 0.28.0 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "syntex"
 version = "0.29.0"
@@ -677,19 +669,6 @@ dependencies = [
  "syntex_syntax 0.29.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "syntex_syntax"
-version = "0.28.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "bitflags 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc-serialize 0.3.18 (registry+https://github.com/rust-lang/crates.io-index)",
- "term 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
- "unicode-xid 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "syntex_syntax"
 version = "0.29.0"
diff --git a/parity/main.rs b/parity/main.rs
index 4238a9333..3279e1fed 100644
--- a/parity/main.rs
+++ b/parity/main.rs
@@ -17,7 +17,7 @@
 //! Ethcore client application.
 
 #![warn(missing_docs)]
-#![feature(plugin)]
+#![cfg_attr(feature="dev", feature(plugin))]
 #![cfg_attr(feature="dev", plugin(clippy))]
 extern crate docopt;
 extern crate rustc_serialize;
diff --git a/rpc/Cargo.toml b/rpc/Cargo.toml
index f179b0c66..5e25b7901 100644
--- a/rpc/Cargo.toml
+++ b/rpc/Cargo.toml
@@ -23,7 +23,7 @@ serde_macros = { version = "0.6.13", optional = true }
 
 [build-dependencies]
 serde_codegen = { "version" = "0.6.13", "optional" = true }
-syntex = "0.28.0"
+syntex = "0.29.0"
 
 [features]
 default = ["serde_codegen"]
diff --git a/sync/src/lib.rs b/sync/src/lib.rs
index e80a89e50..d6bce2447 100644
--- a/sync/src/lib.rs
+++ b/sync/src/lib.rs
@@ -17,7 +17,6 @@
 #![warn(missing_docs)]
 #![cfg_attr(feature="dev", feature(plugin))]
 #![cfg_attr(feature="dev", plugin(clippy))]
-#![feature(augmented_assignments)]
 // Keeps consistency (all lines with `.clone()`) and helpful when changing ref to non-ref.
 #![allow(clone_on_copy)]
 
@@ -59,7 +58,7 @@ use std::ops::*;
 use std::sync::*;
 use ethcore::client::Client;
 use util::network::{NetworkProtocolHandler, NetworkService, NetworkContext, PeerId};
-use util::io::TimerToken;
+use util::TimerToken;
 use chain::ChainSync;
 use ethcore::service::SyncMessage;
 use io::NetSyncIo;
diff --git a/sync/src/tests/helpers.rs b/sync/src/tests/helpers.rs
index c561b65a3..8c8b3b10a 100644
--- a/sync/src/tests/helpers.rs
+++ b/sync/src/tests/helpers.rs
@@ -213,7 +213,10 @@ impl BlockChainClient for TestBlockChainClient {
 		}
 		let len = self.numbers.read().unwrap().len();
 		if number == len {
-			*self.difficulty.write().unwrap().deref_mut() += header.difficulty;
+			{
+				let mut difficulty = self.difficulty.write().unwrap();
+				*difficulty.deref_mut() = *difficulty.deref() + header.difficulty;
+			}
 			mem::replace(self.last_hash.write().unwrap().deref_mut(), h.clone());
 			self.blocks.write().unwrap().insert(h.clone(), b);
 			self.numbers.write().unwrap().insert(number, h.clone());