diff --git a/polkadot/Cargo.lock b/polkadot/Cargo.lock
index 7e747b44e6..a7e9516b0b 100644
--- a/polkadot/Cargo.lock
+++ b/polkadot/Cargo.lock
@@ -5,7 +5,7 @@ name = "adder"
 version = "0.1.0"
 dependencies = [
  "dlmalloc 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-parachain 0.1.0",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-wasm-builder-runner 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -225,11 +225,6 @@ name = "bitmask"
 version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "bitvec"
-version = "0.8.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "bitvec"
 version = "0.11.3"
@@ -309,6 +304,11 @@ name = "bumpalo"
 version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "byte-slice-cast"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "byte-tools"
 version = "0.2.0"
@@ -725,7 +725,7 @@ dependencies = [
  "hashmap_core 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -765,7 +765,7 @@ name = "fork-tree"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1142,7 +1142,7 @@ name = "impl-codec"
 version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2176,11 +2176,12 @@ source = "git+https://github.com/paritytech/parity-common?rev=b0317f649ab2c665b7
 
 [[package]]
 name = "parity-codec"
-version = "4.1.3"
+version = "4.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "arrayvec 0.4.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitvec 0.11.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "byte-slice-cast 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "parity-codec-derive 3.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -2404,7 +2405,7 @@ dependencies = [
  "kvdb-memorydb 0.1.0 (git+https://github.com/paritytech/parity-common?rev=616b40150ded71f57f650067fcbc5c99d7c343e6)",
  "kvdb-rocksdb 0.1.4 (git+https://github.com/paritytech/parity-common?rev=616b40150ded71f57f650067fcbc5c99d7c343e6)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-primitives 0.1.0",
  "substrate-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -2430,7 +2431,7 @@ dependencies = [
  "futures 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures-preview 0.3.0-alpha.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-cli 0.5.0",
  "polkadot-network 0.1.0",
  "polkadot-primitives 0.1.0",
@@ -2449,7 +2450,7 @@ dependencies = [
 name = "polkadot-erasure-coding"
 version = "0.1.0"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-primitives 0.1.0",
  "reed-solomon-erasure 4.0.0 (git+https://github.com/paritytech/reed-solomon-erasure)",
  "substrate-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -2472,7 +2473,7 @@ dependencies = [
  "exit-future 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-availability-store 0.1.0",
  "polkadot-primitives 0.1.0",
@@ -2494,7 +2495,7 @@ dependencies = [
  "halt 0.1.0",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "shared_memory 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2507,7 +2508,8 @@ dependencies = [
 name = "polkadot-primitives"
 version = "0.1.0"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bitvec 0.11.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-parachain 0.1.0",
  "pretty_assertions 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2523,11 +2525,11 @@ dependencies = [
 name = "polkadot-runtime"
 version = "0.1.0"
 dependencies = [
- "bitvec 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bitvec 0.11.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "hex-literal 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libsecp256k1 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-primitives 0.1.0",
  "rustc-hex 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2602,7 +2604,7 @@ dependencies = [
 name = "polkadot-statement-table"
 version = "0.1.0"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-primitives 0.1.0",
  "substrate-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
 ]
@@ -2611,13 +2613,14 @@ dependencies = [
 name = "polkadot-validation"
 version = "0.1.0"
 dependencies = [
+ "bitvec 0.11.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "derive_more 0.14.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "exit-future 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures-preview 0.3.0-alpha.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures-timer 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-availability-store 0.1.0",
  "polkadot-parachain 0.1.0",
@@ -3273,7 +3276,7 @@ dependencies = [
  "environmental 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "hash-db 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libsecp256k1 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3290,7 +3293,7 @@ dependencies = [
  "integer-sqrt 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "paste 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3312,7 +3315,7 @@ version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
  "impl-serde 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3323,7 +3326,7 @@ name = "srml-aura"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3342,7 +3345,7 @@ name = "srml-authorship"
 version = "0.1.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3356,7 +3359,7 @@ name = "srml-balances"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3371,7 +3374,7 @@ name = "srml-collective"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3387,7 +3390,7 @@ name = "srml-democracy"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3402,7 +3405,7 @@ name = "srml-elections"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3418,7 +3421,7 @@ name = "srml-executive"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3432,7 +3435,7 @@ name = "srml-finality-tracker"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3446,7 +3449,7 @@ name = "srml-grandpa"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3463,7 +3466,7 @@ name = "srml-indices"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3480,7 +3483,7 @@ name = "srml-metadata"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3491,7 +3494,7 @@ name = "srml-session"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3508,7 +3511,7 @@ name = "srml-staking"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3526,7 +3529,7 @@ name = "srml-sudo"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3543,7 +3546,7 @@ source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e
 dependencies = [
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "paste 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3594,7 +3597,7 @@ name = "srml-system"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3609,7 +3612,7 @@ name = "srml-timestamp"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3623,7 +3626,7 @@ name = "srml-treasury"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3762,7 +3765,7 @@ dependencies = [
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  "kvdb 0.1.0 (git+https://github.com/paritytech/parity-common?rev=b0317f649ab2c665b7987b8475878fc4d2e1f81d)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-api-macros 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3789,7 +3792,7 @@ dependencies = [
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  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "substrate-client 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3810,7 +3813,7 @@ dependencies = [
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  "futures-timer 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-io 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3831,7 +3834,7 @@ name = "substrate-consensus-aura-primitives"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
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  "substrate-client 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3848,7 +3851,7 @@ dependencies = [
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  "libp2p 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
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  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3865,7 +3868,7 @@ dependencies = [
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  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
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  "substrate-client 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3884,7 +3887,7 @@ dependencies = [
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  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
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  "sr-version 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3907,7 +3910,7 @@ dependencies = [
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  "futures-preview 0.3.0-alpha.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
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  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3930,7 +3933,7 @@ name = "substrate-finality-grandpa-primitives"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3943,7 +3946,7 @@ name = "substrate-inherents"
 version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
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  "sr-std 2.0.0 (git+https://github.com/paritytech/substrate?branch=polkadot-master)",
@@ -3994,7 +3997,7 @@ dependencies = [
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -4021,7 +4024,7 @@ source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e
 dependencies = [
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -4077,7 +4080,7 @@ dependencies = [
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -4186,7 +4189,7 @@ version = "2.0.0"
 source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e5a3742cfecb7f8f89c7c961ae900cca645b65"
 dependencies = [
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -4251,7 +4254,7 @@ dependencies = [
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -4266,7 +4269,7 @@ source = "git+https://github.com/paritytech/substrate?branch=polkadot-master#f9e
 dependencies = [
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- "parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
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-"checksum bitvec 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e37e2176261200377c7cde4c6de020394174df556c356f965e4bc239f5ce1c5a"
 "checksum blake2 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "91721a6330935673395a0607df4d49a9cb90ae12d259f1b3e0a3f6e1d486872e"
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 "checksum block-buffer 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1339a1042f5d9f295737ad4d9a6ab6bf81c84a933dba110b9200cd6d1448b814"
@@ -5093,6 +5095,7 @@ dependencies = [
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 "checksum bstr 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "e0a692f1c740e7e821ca71a22cf99b9b2322dfa94d10f71443befb1797b3946a"
 "checksum bumpalo 2.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2cd43d82f27d68911e6ee11ee791fb248f138f5d69424dc02e098d4f152b0b05"
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 "checksum byte-tools 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "560c32574a12a89ecd91f5e742165893f86e3ab98d21f8ea548658eb9eef5f40"
 "checksum byte-tools 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e3b5ca7a04898ad4bcd41c90c5285445ff5b791899bb1b0abdd2a2aa791211d7"
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@@ -5283,7 +5286,7 @@ dependencies = [
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 "checksum parity-bytes 0.1.0 (git+https://github.com/paritytech/parity-common?rev=616b40150ded71f57f650067fcbc5c99d7c343e6)" = "<none>"
 "checksum parity-bytes 0.1.0 (git+https://github.com/paritytech/parity-common?rev=b0317f649ab2c665b7987b8475878fc4d2e1f81d)" = "<none>"
-"checksum parity-codec 4.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2900f06356edf90de66a2922db622b36178dca71e85625eae58d0d9cc6cff2ac"
+"checksum parity-codec 4.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "7c1a0e8c54ce49245caa93c1a4e11dc4da1d1e9cc8649ff30e57aa177d4abd55"
 "checksum parity-codec-derive 3.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "00a486fd383382ddcb2de928364b1f82571c1e48274fc43b7667a4738ee4056c"
 "checksum parity-multiaddr 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "045b3c7af871285146300da35b1932bb6e4639b66c7c98e85d06a32cbc4e8fa7"
 "checksum parity-multihash 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "df3a17dc27848fd99e4f87eb0f8c9baba6ede0a6d555400c850ca45254ef4ce3"
diff --git a/polkadot/primitives/Cargo.toml b/polkadot/primitives/Cargo.toml
index a775e14435..21726738b0 100644
--- a/polkadot/primitives/Cargo.toml
+++ b/polkadot/primitives/Cargo.toml
@@ -6,13 +6,14 @@ edition = "2018"
 
 [dependencies]
 serde = { version = "1.0", optional = true, features = ["derive"] }
-parity-codec = { version = "4.1", default-features = false }
+parity-codec = { version = "4.1", default-features = false, features = ["bit-vec"] }
 primitives = { package = "substrate-primitives", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 substrate-client = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 sr-version = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 rstd = { package = "sr-std", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 runtime_primitives = { package = "sr-primitives", git = "https://github.com/paritytech/substrate", default-features = false, branch = "polkadot-master" }
 polkadot-parachain = { path = "../parachain", default-features = false }
+bitvec = { version = "0.11", default-features = false, features = ["alloc"] }
 
 [dev-dependencies]
 substrate-serializer = { git = "https://github.com/paritytech/substrate", branch = "polkadot-master" }
@@ -29,4 +30,5 @@ std = [
 	"runtime_primitives/std",
 	"serde",
 	"polkadot-parachain/std",
+	"bitvec/std"
 ]
diff --git a/polkadot/primitives/src/parachain.rs b/polkadot/primitives/src/parachain.rs
index e8ffc48856..d846f90a82 100644
--- a/polkadot/primitives/src/parachain.rs
+++ b/polkadot/primitives/src/parachain.rs
@@ -19,6 +19,7 @@
 use rstd::prelude::*;
 use rstd::cmp::Ordering;
 use parity_codec::{Encode, Decode};
+use bitvec::vec::BitVec;
 use super::{Hash, Balance, BlockNumber};
 
 #[cfg(feature = "std")]
@@ -305,7 +306,9 @@ pub struct AttestedCandidate {
 	/// The candidate data.
 	pub candidate: CandidateReceipt,
 	/// Validity attestations.
-	pub validity_votes: Vec<(ValidatorIndex, ValidityAttestation)>,
+	pub validity_votes: Vec<ValidityAttestation>,
+	/// Indices of the corresponding validity votes.
+	pub validator_indices: BitVec,
 }
 
 impl AttestedCandidate {
diff --git a/polkadot/runtime/Cargo.toml b/polkadot/runtime/Cargo.toml
index 8c55ffed33..943fe17fc5 100644
--- a/polkadot/runtime/Cargo.toml
+++ b/polkadot/runtime/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2018"
 build = "build.rs"
 
 [dependencies]
-bitvec = { version = "0.8", default-features = false, features = ["alloc"] }
+bitvec = { version = "0.11", default-features = false, features = ["alloc"] }
 rustc-hex = { version = "2.0.1", default-features = false }
 log = { version = "0.3", optional = true }
 serde = { version = "1.0", default-features = false }
diff --git a/polkadot/runtime/src/parachains.rs b/polkadot/runtime/src/parachains.rs
index 1030e91c79..f4083777bf 100644
--- a/polkadot/runtime/src/parachains.rs
+++ b/polkadot/runtime/src/parachains.rs
@@ -21,7 +21,6 @@ use rstd::collections::btree_map::BTreeMap;
 use parity_codec::{Decode, HasCompact};
 use srml_support::{decl_storage, decl_module, fail, ensure};
 
-use bitvec::{bitvec, BigEndian};
 use sr_primitives::traits::{Hash as HashT, BlakeTwo256, Member, CheckedConversion, Saturating, One};
 use sr_primitives::weights::SimpleDispatchInfo;
 use primitives::{Hash, Balance, parachain::{
@@ -726,6 +725,11 @@ impl<T: Trait> Module<T> {
 				"Not enough validity attestations"
 			);
 
+			ensure!(
+				candidate.validity_votes.len() <= authorities.len(),
+				"The number of attestations exceeds the number of authorities"
+			);
+
 			let fees = candidate.candidate().fees;
 			T::ParachainCurrency::deduct(para_id, fees)?;
 
@@ -733,19 +737,15 @@ impl<T: Trait> Module<T> {
 			let mut encoded_implicit = None;
 			let mut encoded_explicit = None;
 
-			// track which voters have voted already, 1 bit per authority.
-			let mut track_voters = bitvec![0; authorities.len()];
-			for (auth_index, validity_attestation) in &candidate.validity_votes {
-				let auth_index = *auth_index as usize;
-				// protect against double-votes.
-				match validator_group.iter().find(|&(idx, _)| *idx == auth_index) {
-					None => return Err("Attesting validator not on this chain's validation duty."),
-					Some(&(idx, _)) => {
-						if track_voters.get(idx) {
-							return Err("Voter already attested validity once")
-						}
-						track_voters.set(idx, true)
-					}
+			for ((auth_index, _), validity_attestation) in candidate.validator_indices
+				.iter()
+				.enumerate()
+				.filter(|(_, bit)| *bit)
+				.zip(candidate.validity_votes.iter())
+			{
+
+				if validator_group.iter().find(|&(idx, _)| *idx == auth_index).is_none() {
+					return Err("Attesting validator not on this chain's validation duty.");
 				}
 
 				let (payload, sig) = match validity_attestation {
@@ -818,6 +818,7 @@ impl<T: Trait> ProvideInherent for Module<T> {
 mod tests {
 	use super::*;
 	use super::Call as ParachainsCall;
+	use bitvec::{bitvec, vec::BitVec};
 	use sr_io::{TestExternalities, with_externalities};
 	use substrate_primitives::{H256, Blake2Hasher};
 	use substrate_trie::NodeCodec;
@@ -827,7 +828,7 @@ mod tests {
 		testing::{UintAuthorityId, Header},
 	};
 	use primitives::{
-		parachain::{CandidateReceipt, HeadData, ValidityAttestation, ValidatorIndex}, SessionKey,
+		parachain::{CandidateReceipt, HeadData, ValidityAttestation}, SessionKey,
 		BlockNumber, AuraId,
 	};
 	use keyring::Ed25519Keyring;
@@ -1004,6 +1005,7 @@ mod tests {
 		let validation_entries = duty_roster.validator_duty.iter()
 			.enumerate();
 
+		let mut validator_indices = BitVec::new();
 		for (idx, &duty) in validation_entries {
 			if duty != Chain::Parachain(candidate.parachain_index()) { continue }
 			vote_implicit = !vote_implicit;
@@ -1019,17 +1021,24 @@ mod tests {
 			let payload = localized_payload(statement, parent_hash);
 			let signature = key.sign(&payload[..]).into();
 
-			candidate.validity_votes.push((idx as ValidatorIndex, if vote_implicit {
+			candidate.validity_votes.push(if vote_implicit {
 				ValidityAttestation::Implicit(signature)
 			} else {
 				ValidityAttestation::Explicit(signature)
-			}));
+			});
+
+			if validator_indices.len() <= idx {
+				validator_indices.resize(idx + 1, false);
+			}
+			validator_indices.set(idx, true);
 		}
+		candidate.validator_indices = validator_indices;
 	}
 
 	fn new_candidate_with_egress_roots(egress_queue_roots: Vec<(ParaId, H256)>) -> AttestedCandidate {
 		AttestedCandidate {
 			validity_votes: vec![],
+			validator_indices: BitVec::new(),
 			candidate: CandidateReceipt {
 				parachain_index: 0.into(),
 				collator: Default::default(),
@@ -1049,6 +1058,7 @@ mod tests {
 	) -> AttestedCandidate {
 		AttestedCandidate {
 			validity_votes: vec![],
+			validator_indices: BitVec::new(),
 			candidate: CandidateReceipt {
 				parachain_index: id.into(),
 				collator: Default::default(),
@@ -1411,6 +1421,7 @@ mod tests {
 		with_externalities(&mut new_test_ext(parachains), || {
 			let candidate = AttestedCandidate {
 				validity_votes: vec![],
+				validator_indices: BitVec::new(),
 				candidate: CandidateReceipt {
 					parachain_index: 0.into(),
 					collator: Default::default(),
@@ -1438,6 +1449,7 @@ mod tests {
 		with_externalities(&mut new_test_ext(parachains), || {
 			let mut candidate_a = AttestedCandidate {
 				validity_votes: vec![],
+				validator_indices: BitVec::new(),
 				candidate: CandidateReceipt {
 					parachain_index: 0.into(),
 					collator: Default::default(),
@@ -1452,6 +1464,7 @@ mod tests {
 
 			let mut candidate_b = AttestedCandidate {
 				validity_votes: vec![],
+				validator_indices: BitVec::new(),
 				candidate: CandidateReceipt {
 					parachain_index: 1.into(),
 					collator: Default::default(),
@@ -1489,6 +1502,7 @@ mod tests {
 		with_externalities(&mut new_test_ext(parachains), || {
 			let mut candidate = AttestedCandidate {
 				validity_votes: vec![],
+				validator_indices: BitVec::new(),
 				candidate: CandidateReceipt {
 					parachain_index: 0.into(),
 					collator: Default::default(),
@@ -1505,6 +1519,7 @@ mod tests {
 
 			let mut double_validity = candidate.clone();
 			double_validity.validity_votes.push(candidate.validity_votes[0].clone());
+			double_validity.validator_indices.push(true);
 
 			assert!(Parachains::dispatch(
 				set_heads(vec![double_validity]),
@@ -1513,6 +1528,42 @@ mod tests {
 		});
 	}
 
+	#[test]
+	fn validators_not_from_group_is_rejected() {
+		let parachains = vec![
+			(0u32.into(), vec![], vec![]),
+			(1u32.into(), vec![], vec![]),
+		];
+
+		with_externalities(&mut new_test_ext(parachains), || {
+			let mut candidate = AttestedCandidate {
+				validity_votes: vec![],
+				validator_indices: BitVec::new(),
+				candidate: CandidateReceipt {
+					parachain_index: 0.into(),
+					collator: Default::default(),
+					signature: Default::default(),
+					head_data: HeadData(vec![1, 2, 3]),
+					egress_queue_roots: vec![],
+					fees: 0,
+					block_data_hash: Default::default(),
+					upward_messages: vec![],
+				}
+			};
+
+			make_attestations(&mut candidate);
+
+			// Change the last vote index to make it not corresponding to the assigned group.
+			assert!(candidate.validator_indices.pop().is_some());
+			candidate.validator_indices.append(&mut bitvec![0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1]);
+
+			assert!(Parachains::dispatch(
+				set_heads(vec![candidate]),
+				Origin::NONE,
+			).is_err());
+		});
+	}
+
 	#[test]
 	fn ingress_works() {
 		use sr_primitives::traits::OnFinalize;
@@ -1533,6 +1584,7 @@ mod tests {
 				let from_a = vec![(1.into(), [i as u8; 32].into())];
 				let mut candidate_a = AttestedCandidate {
 					validity_votes: vec![],
+					validator_indices: BitVec::new(),
 					candidate: CandidateReceipt {
 						parachain_index: 0.into(),
 						collator: Default::default(),
@@ -1548,6 +1600,7 @@ mod tests {
 				let from_b = vec![(99.into(), [i as u8; 32].into())];
 				let mut candidate_b = AttestedCandidate {
 					validity_votes: vec![],
+					validator_indices: BitVec::new(),
 					candidate: CandidateReceipt {
 						parachain_index: 1.into(),
 						collator: Default::default(),
@@ -1611,6 +1664,7 @@ mod tests {
 
 			let mut candidate_c = AttestedCandidate {
 				validity_votes: vec![],
+				validator_indices: BitVec::new(),
 				candidate: CandidateReceipt {
 					parachain_index: 99.into(),
 					collator: Default::default(),
diff --git a/polkadot/test-parachains/adder/Cargo.toml b/polkadot/test-parachains/adder/Cargo.toml
index 39a8a66f80..e8e8b5cbb9 100644
--- a/polkadot/test-parachains/adder/Cargo.toml
+++ b/polkadot/test-parachains/adder/Cargo.toml
@@ -26,4 +26,4 @@ no_std = [
 	"parachain/wasm-api",
 	"dlmalloc",
 ]
-std = []
\ No newline at end of file
+std = []
diff --git a/polkadot/validation/Cargo.toml b/polkadot/validation/Cargo.toml
index 0b4b944191..e50438f6b5 100644
--- a/polkadot/validation/Cargo.toml
+++ b/polkadot/validation/Cargo.toml
@@ -30,6 +30,7 @@ runtime_aura = { package = "srml-aura", git = "https://github.com/paritytech/sub
 client = { package = "substrate-client", git = "https://github.com/paritytech/substrate", branch = "polkadot-master" }
 trie = { package = "substrate-trie", git = "https://github.com/paritytech/substrate", branch = "polkadot-master" }
 runtime_primitives = { package = "sr-primitives", git = "https://github.com/paritytech/substrate", branch = "polkadot-master" }
+bitvec = { version = "0.11", default-features = false, features = ["alloc"] }
 
 [dev-dependencies]
 substrate-keyring = { git = "https://github.com/paritytech/substrate", branch = "polkadot-master" }
diff --git a/polkadot/validation/src/shared_table/mod.rs b/polkadot/validation/src/shared_table/mod.rs
index a72d4ab1ea..85fa3e8eba 100644
--- a/polkadot/validation/src/shared_table/mod.rs
+++ b/polkadot/validation/src/shared_table/mod.rs
@@ -30,6 +30,7 @@ use polkadot_primitives::parachain::{Id as ParaId, Collation, Extrinsic, Candida
 use parking_lot::Mutex;
 use futures::prelude::*;
 use log::{warn, debug};
+use bitvec::bitvec;
 
 use super::{GroupInfo, TableRouter};
 use self::includable::IncludabilitySender;
@@ -519,14 +520,26 @@ impl SharedTable {
 		// aggregation in the future.
 		let table_attestations = self.inner.lock().table.proposed_candidates(&*self.context);
 		table_attestations.into_iter()
-			.map(|attested| AttestedCandidate {
-				candidate: attested.candidate,
-				validity_votes: attested.validity_votes.into_iter().map(|(a, v)| match v {
-					GAttestation::Implicit(s) => (a, ValidityAttestation::Implicit(s)),
-					GAttestation::Explicit(s) => (a, ValidityAttestation::Explicit(s)),
-				}).collect(),
-			})
-			.collect()
+			.map(|attested| {
+				let mut validity_votes: Vec<_> = attested.validity_votes.into_iter().map(|(id, a)| {
+					(id as usize, match a {
+						GAttestation::Implicit(s) => ValidityAttestation::Implicit(s),
+						GAttestation::Explicit(s) => ValidityAttestation::Explicit(s),
+					})
+				}).collect();
+				validity_votes.sort_by(|(id1, _), (id2, _)| id1.cmp(id2));
+
+				let mut validator_indices = bitvec![0; validity_votes.last().map(|(i, _)| i + 1).unwrap_or_default()];
+				for (id, _) in &validity_votes {
+					validator_indices.set(*id, true);
+				}
+
+				AttestedCandidate {
+					candidate: attested.candidate,
+					validity_votes: validity_votes.into_iter().map(|(_, a)| a).collect(),
+					validator_indices,
+				}
+			}).collect()
 	}
 
 	/// Get the number of total parachains.