diff --git a/ethcore/res/ethereum/frontier.json b/ethcore/res/ethereum/frontier.json
index 7a1662d8c..8f9209179 100644
--- a/ethcore/res/ethereum/frontier.json
+++ b/ethcore/res/ethereum/frontier.json
@@ -33,10 +33,10 @@
 		"enode://248f12bc8b18d5289358085520ac78cd8076485211e6d96ab0bc93d6cd25442db0ce3a937dc404f64f207b0b9aed50e25e98ce32af5ac7cb321ff285b97de485@parity-node-zero.ethcore.io:30303"
 	],
 	"accounts": {
-		"0000000000000000000000000000000000000001": { "builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } } },
-		"0000000000000000000000000000000000000002": { "builtin": { "name": "sha256", "pricing": { "base": 60, "word": 12 } } },
-		"0000000000000000000000000000000000000003": { "builtin": { "name": "ripemd160", "pricing": { "base": 600, "word": 120 } } },
-		"0000000000000000000000000000000000000004": { "builtin": { "name": "identity", "pricing": { "base": 15, "word": 3 } } },
+		"0000000000000000000000000000000000000001": { "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
 		"3282791d6fd713f1e94f4bfd565eaa78b3a0599d": {
 			"balance": "1337000000000000000000"
 		},
diff --git a/ethcore/res/ethereum/frontier_like_test.json b/ethcore/res/ethereum/frontier_like_test.json
index 803e593be..49b39cde7 100644
--- a/ethcore/res/ethereum/frontier_like_test.json
+++ b/ethcore/res/ethereum/frontier_like_test.json
@@ -26,9 +26,9 @@
 		"gasLimit": "0x1388"
 	},
 	"accounts": {
-		"0000000000000000000000000000000000000001": { "builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } } },
-		"0000000000000000000000000000000000000002": { "builtin": { "name": "sha256", "pricing": { "base": 60, "word": 12 } } },
-		"0000000000000000000000000000000000000003": { "builtin": { "name": "ripemd160", "pricing": { "base": 600, "word": 120 } } },
-		"0000000000000000000000000000000000000004": { "builtin": { "name": "identity", "pricing": { "base": 15, "word": 3 } } }
+		"0000000000000000000000000000000000000001": { "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
 	}
 }
diff --git a/ethcore/res/ethereum/frontier_test.json b/ethcore/res/ethereum/frontier_test.json
index f1a75881a..79f47b2e6 100644
--- a/ethcore/res/ethereum/frontier_test.json
+++ b/ethcore/res/ethereum/frontier_test.json
@@ -26,9 +26,9 @@
 		"gasLimit": "0x1388"
 	},
 	"accounts": {
-		"0000000000000000000000000000000000000001": { "builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } } },
-		"0000000000000000000000000000000000000002": { "builtin": { "name": "sha256", "pricing": { "base": 60, "word": 12 } } },
-		"0000000000000000000000000000000000000003": { "builtin": { "name": "ripemd160", "pricing": { "base": 600, "word": 120 } } },
-		"0000000000000000000000000000000000000004": { "builtin": { "name": "identity", "pricing": { "base": 15, "word": 3 } } }
+		"0000000000000000000000000000000000000001": { "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
 	}
 }
diff --git a/ethcore/res/ethereum/homestead_test.json b/ethcore/res/ethereum/homestead_test.json
index 8f13eb042..0f0e630dd 100644
--- a/ethcore/res/ethereum/homestead_test.json
+++ b/ethcore/res/ethereum/homestead_test.json
@@ -26,9 +26,9 @@
 		"gasLimit": "0x1388"
 	},
 	"accounts": {
-		"0000000000000000000000000000000000000001": { "balance": "1", "builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } } },
-		"0000000000000000000000000000000000000002": { "balance": "1", "builtin": { "name": "sha256", "pricing": { "base": 60, "word": 12 } } },
-		"0000000000000000000000000000000000000003": { "balance": "1", "builtin": { "name": "ripemd160", "pricing": { "base": 600, "word": 120 } } },
-		"0000000000000000000000000000000000000004": { "balance": "1", "builtin": { "name": "identity", "pricing": { "base": 15, "word": 3 } } }
+		"0000000000000000000000000000000000000001": { "balance": "1", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "balance": "1", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "balance": "1", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "balance": "1", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } }
 	}
 }
diff --git a/ethcore/res/ethereum/morden.json b/ethcore/res/ethereum/morden.json
index a5230acf4..2cf4785db 100644
--- a/ethcore/res/ethereum/morden.json
+++ b/ethcore/res/ethereum/morden.json
@@ -29,10 +29,10 @@
 		"enode://b1217cbaa440e35ed471157123fe468e19e8b5ad5bedb4b1fdbcbdab6fb2f5ed3e95dd9c24a22a79fdb2352204cea207df27d92bfd21bfd41545e8b16f637499@104.44.138.37:30303"
 	],
 	"accounts": {
-		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } } },
-		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "base": 60, "word": 12 } } },
-		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "base": 600, "word": 120 } } },
-		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "base": 15, "word": 3 } } },
+		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
 		"102e61f5d8f9bc71d0ad4a084df4e65e05ce0e1c": { "balance": "1606938044258990275541962092341162602522202993782792835301376", "nonce": "1048576" }
 	}
 }
diff --git a/ethcore/res/ethereum/olympic.json b/ethcore/res/ethereum/olympic.json
index 872877429..365a8167c 100644
--- a/ethcore/res/ethereum/olympic.json
+++ b/ethcore/res/ethereum/olympic.json
@@ -26,10 +26,10 @@
 		"gasLimit": "0x2fefd8"
 	},
 	"accounts": {
-		"0000000000000000000000000000000000000001": { "balance": "1", "builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } } },
-		"0000000000000000000000000000000000000002": { "balance": "1", "builtin": { "name": "sha256", "pricing": { "base": 60, "word": 12 } } },
-		"0000000000000000000000000000000000000003": { "balance": "1", "builtin": { "name": "ripemd160", "pricing": { "base": 600, "word": 120 } } },
-		"0000000000000000000000000000000000000004": { "balance": "1", "builtin": { "name": "identity", "pricing": { "base": 15, "word": 3 } } },
+		"0000000000000000000000000000000000000001": { "balance": "1", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "balance": "1", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "balance": "1", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "balance": "1", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } }
 		"dbdbdb2cbd23b783741e8d7fcf51e459b497e4a6": { "balance": "1606938044258990275541962092341162602522202993782792835301376" },
 		"e6716f9544a56c530d868e4bfbacb172315bdead": { "balance": "1606938044258990275541962092341162602522202993782792835301376" },
 		"b9c015918bdaba24b4ff057a92a3873d6eb201be": { "balance": "1606938044258990275541962092341162602522202993782792835301376" },
diff --git a/ethcore/res/null_morden.json b/ethcore/res/null_morden.json
index 49795c337..70b48fbdb 100644
--- a/ethcore/res/null_morden.json
+++ b/ethcore/res/null_morden.json
@@ -26,10 +26,10 @@
 		"gasLimit": "0x2fefd8"
 	},
 	"accounts": {
-		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } } },
-		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "base": 60, "word": 12 } } },
-		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "base": 600, "word": 120 } } },
-		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "base": 15, "word": 3 } } },
+		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
 		"102e61f5d8f9bc71d0ad4a084df4e65e05ce0e1c": { "balance": "1606938044258990275541962092341162602522202993782792835301376", "nonce": "1048576" }
 	}
 }
diff --git a/ethcore/src/builtin.rs b/ethcore/src/builtin.rs
index 0e857335e..2ee8e24b1 100644
--- a/ethcore/src/builtin.rs
+++ b/ethcore/src/builtin.rs
@@ -68,9 +68,11 @@ impl Builtin {
 		// NICE: figure out a more convenient means of handing errors here.
 		if let Json::String(ref name) = json["name"] {
 			if let Json::Object(ref o) = json["pricing"] {
-				if let Json::U64(ref word) = o["word"] {
-					if let Json::U64(ref base) = o["base"] {
-						return Self::from_named_linear(&name[..], *base as usize, *word as usize);
+				if let Json::Object(ref o) = o["linear"] {
+					if let Json::U64(ref word) = o["word"] {
+						if let Json::U64(ref base) = o["base"] {
+							return Self::from_named_linear(&name[..], *base as usize, *word as usize);
+						}
 					}
 				}
 			}
@@ -274,7 +276,7 @@ fn from_named_linear() {
 
 #[test]
 fn from_json() {
-	let text = "{ \"name\": \"identity\", \"pricing\": {\"base\": 10, \"word\": 20} }";
+	let text = r#"{"name": "identity", "pricing": {"linear": {"base": 10, "word": 20}}}"#;
 	let json = Json::from_str(text).unwrap();
 	let b = Builtin::from_json(&json).unwrap();
 	assert_eq!((*b.cost)(0), U256::from(10));
diff --git a/json/src/spec/account.rs b/json/src/spec/account.rs
index f4cce3fc8..1440b1bdc 100644
--- a/json/src/spec/account.rs
+++ b/json/src/spec/account.rs
@@ -36,7 +36,7 @@ mod tests {
 	fn account_deserialization() {
 		let s = r#"{
 			"balance": "1",
-			"builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } }
+			"builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } }
 		}"#;
 		let _deserialized: Account = serde_json::from_str(s).unwrap();
 		// TODO: validate all fields
diff --git a/json/src/spec/builtin.rs b/json/src/spec/builtin.rs
index 24f83b1d6..21f8a2ac1 100644
--- a/json/src/spec/builtin.rs
+++ b/json/src/spec/builtin.rs
@@ -16,8 +16,6 @@
 
 //! Spec builtin deserialization.
 
-use serde::de::{Deserialize, Deserializer};
-
 /// Linear pricing.
 #[derive(Debug, PartialEq, Deserialize)]
 pub struct Linear {
@@ -26,20 +24,13 @@ pub struct Linear {
 }
 
 /// Pricing variants.
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Deserialize)]
 pub enum Pricing {
 	/// Linear pricing.
+	#[serde(rename="linear")]
 	Linear(Linear),
 }
 
-impl Deserialize for Pricing {
-	fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error>
-		where D: Deserializer {
-			Deserialize::deserialize(deserializer).map(Pricing::Linear)
-	}
-}
-
-
 /// Spec builtin.
 #[derive(Debug, PartialEq, Deserialize)]
 pub struct Builtin {
@@ -56,7 +47,7 @@ mod tests {
 	fn builtin_deserialization() {
 		let s = r#"{
 			"name": "ecrecover",
-			"pricing": { "base": 3000, "word": 0 }
+			"pricing": { "linear": { "base": 3000, "word": 0 } }
 		}"#;
 		let _deserialized: Builtin = serde_json::from_str(s).unwrap();
 		// TODO: validate all fields
diff --git a/json/src/spec/spec.rs b/json/src/spec/spec.rs
index 0d17d0829..2dd4ac486 100644
--- a/json/src/spec/spec.rs
+++ b/json/src/spec/spec.rs
@@ -71,10 +71,10 @@ mod tests {
 		"enode://b1217cbaa440e35ed471157123fe468e19e8b5ad5bedb4b1fdbcbdab6fb2f5ed3e95dd9c24a22a79fdb2352204cea207df27d92bfd21bfd41545e8b16f637499@104.44.138.37:30303"
 	],
 	"accounts": {
-		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "base": 3000, "word": 0 } } },
-		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "base": 60, "word": 12 } } },
-		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "base": 600, "word": 120 } } },
-		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "base": 15, "word": 3 } } },
+		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
 		"102e61f5d8f9bc71d0ad4a084df4e65e05ce0e1c": { "balance": "1606938044258990275541962092341162602522202993782792835301376", "nonce": "1048576" }
 	}
 		}"#;