diff --git a/Cargo.lock b/Cargo.lock
index ff4c277e53f..ff3bd4d4a8f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -896,13 +896,13 @@ dependencies = [
  "ethereum-types 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "ethjson 0.1.0",
  "ethkey 0.3.0",
+ "hex-literal 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "keccak-hash 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "macros 0.1.0",
  "num 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "parity-bytes 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "parity-crypto 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc-hex 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1264,6 +1264,7 @@ name = "ethjson"
 version = "0.1.0"
 dependencies = [
  "ethereum-types 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "macros 0.1.0",
  "rustc-hex 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/ethcore/builtin/Cargo.toml b/ethcore/builtin/Cargo.toml
index 086ed47bb98..d3ca27a6298 100644
--- a/ethcore/builtin/Cargo.toml
+++ b/ethcore/builtin/Cargo.toml
@@ -20,4 +20,4 @@ parity-bytes = "0.1"
 parity-crypto = "0.4.0"
 
 [dev-dependencies]
-rustc-hex = "1.0"
+hex-literal = "0.2.1"
diff --git a/ethcore/builtin/src/lib.rs b/ethcore/builtin/src/lib.rs
index 1e226be8cf9..3546e7d2453 100644
--- a/ethcore/builtin/src/lib.rs
+++ b/ethcore/builtin/src/lib.rs
@@ -58,12 +58,12 @@ pub type Blake2FPricer = u64;
 impl Pricer for Blake2FPricer {
 	fn cost(&self, input: &[u8]) -> U256 {
 		const FOUR: usize = std::mem::size_of::<u32>();
-		let (rounds_bytes, _) = input.split_at(std::mem::size_of::<u32>());
 		// Returning zero if the conversion fails is fine because `execute()` will check the length
 		// and bail with the appropriate error.
 		if input.len() < FOUR {
 			return U256::zero();
 		}
+		let (rounds_bytes, _) = input.split_at(FOUR);
 		let rounds = u32::from_be_bytes(rounds_bytes.try_into().unwrap_or([0u8; 4]));
 		U256::from(*self as u64 * rounds as u64)
 	}
@@ -743,6 +743,7 @@ impl Bn128Pairing {
 
 #[cfg(test)]
 mod tests {
+	use std::convert::TryFrom;
 	use ethereum_types::U256;
 	use ethjson::spec::builtin::{
 		Builtin as JsonBuiltin, Linear as JsonLinearPricing,
@@ -751,7 +752,6 @@ mod tests {
 	use hex_literal::hex;
 	use macros::map;
 	use num::{BigUint, Zero, One};
-	use hex_literal::hex;
 	use parity_bytes::BytesRef;
 	use super::{
 		BTreeMap, Builtin, EthereumBuiltin, FromStr, Implementation, Linear,
@@ -793,7 +793,7 @@ mod tests {
 
 		let result = blake2.execute(&input[..], &mut BytesRef::Fixed(&mut out[..]));
 		assert!(result.is_err());
-		assert_eq!(result.unwrap_err(), "input length for Blake2 F precompile should be exactly 213 bytes".into());
+		assert_eq!(result.unwrap_err(), "input length for Blake2 F precompile should be exactly 213 bytes");
 	}
 
 	#[test]
@@ -805,7 +805,7 @@ mod tests {
 
 		let result = blake2.execute(&input[..], &mut BytesRef::Fixed(&mut out[..]));
 		assert!(result.is_err());
-		assert_eq!(result.unwrap_err(), "input length for Blake2 F precompile should be exactly 213 bytes".into());
+		assert_eq!(result.unwrap_err(), "input length for Blake2 F precompile should be exactly 213 bytes");
 	}
 
 	#[test]
@@ -817,7 +817,7 @@ mod tests {
 
 		let result = blake2.execute(&input[..], &mut BytesRef::Fixed(&mut out[..]));
 		assert!(result.is_err());
-		assert_eq!(result.unwrap_err(), "incorrect final block indicator flag".into());
+		assert_eq!(result.unwrap_err(), "incorrect final block indicator flag");
 	}
 
 	#[test]
@@ -1337,7 +1337,7 @@ mod tests {
 
 	#[test]
 	fn from_json() {
-		let b = Builtin::from(ethjson::spec::Builtin {
+		let b = Builtin::try_from(ethjson::spec::Builtin {
 			name: "identity".to_owned(),
 			pricing: map![
 				0 => PricingAt {
@@ -1505,6 +1505,6 @@ mod tests {
 		}).unwrap();
 
 		assert_eq!(b.cost(&[0; 1], 0), U256::from(0), "not activated yet");
-		assert_eq!(b.cost(&[0; 1], 1), U256::from(1_337), "use price #3");
+		assert_eq!(b.cost(&[0; 1], 1), U256::from(1_337));
 	}
 }
diff --git a/json/Cargo.toml b/json/Cargo.toml
index 164ee6bce46..2ec487209eb 100644
--- a/json/Cargo.toml
+++ b/json/Cargo.toml
@@ -11,3 +11,5 @@ serde = "1.0"
 serde_json = "1.0"
 serde_derive = "1.0"
 
+[dev-dependencies]
+macros = { path = "../util/macros" }
diff --git a/json/src/lib.rs b/json/src/lib.rs
index af5d93edfa6..d6857d19858 100644
--- a/json/src/lib.rs
+++ b/json/src/lib.rs
@@ -20,6 +20,9 @@ extern crate serde_json;
 extern crate ethereum_types;
 #[macro_use] extern crate serde_derive;
 
+#[cfg(test)]
+extern crate macros;
+
 pub mod hash;
 pub mod uint;
 pub mod bytes;
diff --git a/json/src/spec/builtin.rs b/json/src/spec/builtin.rs
index ec599999908..19ddfc2c635 100644
--- a/json/src/spec/builtin.rs
+++ b/json/src/spec/builtin.rs
@@ -138,7 +138,6 @@ pub struct PricingAt {
 #[cfg(test)]
 mod tests {
 	use serde_json;
-	use spec::builtin::{Builtin, Pricing, Linear, Modexp};
 	use uint::Uint;
 	use super::{Builtin, BuiltinCompat, BTreeMap, Pricing, PricingAt, Linear, Modexp, AltBn128ConstOperations};
 	use macros::map;