diff --git a/substrate/wasm-runtime/polkadot/src/lib.rs b/substrate/wasm-runtime/polkadot/src/lib.rs
index 500594e31a..b791fefdb7 100644
--- a/substrate/wasm-runtime/polkadot/src/lib.rs
+++ b/substrate/wasm-runtime/polkadot/src/lib.rs
@@ -8,6 +8,7 @@ extern crate runtime_support;
 extern crate rustc_hex;
 
 mod codec;
+#[macro_use]
 mod support;
 mod runtime;
 pub use codec::{endiansensitive, streamreader, joiner, slicable, keyedvec};
diff --git a/substrate/wasm-runtime/polkadot/src/runtime/session.rs b/substrate/wasm-runtime/polkadot/src/runtime/session.rs
index 1112d45249..0a736b3b47 100644
--- a/substrate/wasm-runtime/polkadot/src/runtime/session.rs
+++ b/substrate/wasm-runtime/polkadot/src/runtime/session.rs
@@ -4,6 +4,16 @@ use storage::Storage;
 use primitives::{AccountID, SessionKey, BlockNumber};
 use runtime::{system, staking, consensus};
 
+// TRANSACTION API (available to all transactors)
+
+/// Sets the session key of `_transactor` to `_session`. This doesn't take effect until the next
+/// session.
+pub fn set_key(_transactor: &AccountID, _session: &AccountID) {
+	// TODO: record the new session key for `_transactor`, ready for the next session.
+}
+
+// PUBLIC API (available to other runtime modules)
+
 /// Get the current set of validators. These are the long-term identifiers for the validators
 /// and will be mapped to a session key with the most recent `set_next_session_key`.
 pub fn validators() -> Vec<AccountID> {
@@ -24,17 +34,6 @@ pub fn length() -> BlockNumber {
 	Storage::into(b"con\0bps")
 }
 
-/// Sets the session key of `_transactor` to `_session`. This doesn't take effect until the next
-/// session.
-pub fn set_key(_transactor: &AccountID, _session: &AccountID) {
-	// TODO: record the new session key for `_transactor`, ready for the next session.
-}
-
-/// Move onto next session: register the new authority set.
-pub fn next_session() {
-	// TODO: Call set_authorities() with any new authorities.
-}
-
 /// Hook to be called prior to transaction processing.
 pub fn pre_transactions() {
 	staking::pre_transactions();
@@ -51,3 +50,10 @@ pub fn post_transactions() {
 		next_session();
 	}
 }
+
+// PRIVATE (not available)
+
+/// Move onto next session: register the new authority set.
+fn next_session() {
+	// TODO: Call set_authorities() with any new authorities.
+}
diff --git a/substrate/wasm-runtime/polkadot/src/runtime/staking.rs b/substrate/wasm-runtime/polkadot/src/runtime/staking.rs
index 366ad0668b..9b06602c84 100644
--- a/substrate/wasm-runtime/polkadot/src/runtime/staking.rs
+++ b/substrate/wasm-runtime/polkadot/src/runtime/staking.rs
@@ -3,6 +3,11 @@ use storage::Storage;
 use primitives::{BlockNumber, Balance, AccountID};
 use runtime::{system, session};
 
+// Each validator's stake has one amount in each of three states:
+// - inactive: free to be transferred
+// - active: currently representing a validator
+// - deactivating: recently representing a validator and not yet ready for transfer
+
 /// The length of a staking era in blocks.
 pub fn era_length() -> BlockNumber {
 	sessions_per_era() * session::length()
@@ -13,21 +18,26 @@ pub fn sessions_per_era() -> BlockNumber {
 	Storage::into(b"sta\0spe")
 }
 
+/// The length of a staking era in sessions.
+pub fn lockup_eras() -> BlockNumber {
+	Storage::into(b"sta\0lpe")
+}
+
 /// The era has changed - enact new staking set.
 ///
 /// NOTE: This always happens on a session change.
-pub fn next_era() {
+fn next_era() {
 	// TODO: evaluate desired staking amounts and nominations and optimise to find the best
 	// combination of validators, then use session::set_validators().
 }
 
 /// The balance of a given account.
-pub fn balance(who: &AccountID) -> Balance {
+pub fn balance_inactive(who: &AccountID) -> Balance {
 	Storage::into(&who.to_keyed_vec(b"sta\0bal\0"))
 }
 
 /// Transfer some unlocked staking balance to another staker.
-pub fn transfer_stake(transactor: &AccountID, dest: &AccountID, value: Balance) {
+pub fn transfer_inactive(transactor: &AccountID, dest: &AccountID, value: Balance) {
 	let from_key = transactor.to_keyed_vec(b"sta\0bal\0");
 	let from_balance: Balance = Storage::into(&from_key);
 	assert!(from_balance >= value);
@@ -42,14 +52,14 @@ pub fn transfer_stake(transactor: &AccountID, dest: &AccountID, value: Balance)
 ///
 /// Effects will be felt at the beginning of the next era.
 pub fn stake(_transactor: &AccountID) {
-	unimplemented!()
+	// TODO: record the desire for `_transactor` to activate their stake.
 }
 
 /// Retract the desire to stake for the transactor.
 ///
 /// Effects will be felt at the beginning of the next era.
 pub fn unstake(_transactor: &AccountID) {
-	unimplemented!()
+	// TODO: record the desire for `_transactor` to deactivate their stake.
 }
 
 /// Hook to be called prior to transaction processing.
@@ -88,8 +98,8 @@ mod tests {
 		], };
 
 		with_externalities(&mut t, || {
-			assert_eq!(staking::balance(&one), 42);
-			assert_eq!(staking::balance(&two), 0);
+			assert_eq!(staking::balance_inactive(&one), 42);
+			assert_eq!(staking::balance_inactive(&two), 0);
 		});
 	}
 
@@ -103,9 +113,9 @@ mod tests {
 		], };
 
 		with_externalities(&mut t, || {
-			staking::transfer_stake(&one, &two, 69);
-			assert_eq!(staking::balance(&one), 42);
-			assert_eq!(staking::balance(&two), 69);
+			staking::transfer_inactive(&one, &two, 69);
+			assert_eq!(staking::balance_inactive(&one), 42);
+			assert_eq!(staking::balance_inactive(&two), 69);
 		});
 	}
 }
diff --git a/substrate/wasm-runtime/polkadot/src/runtime/system.rs b/substrate/wasm-runtime/polkadot/src/runtime/system.rs
index 690e1db527..d7abd1835a 100644
--- a/substrate/wasm-runtime/polkadot/src/runtime/system.rs
+++ b/substrate/wasm-runtime/polkadot/src/runtime/system.rs
@@ -60,12 +60,6 @@ pub fn execute_block(mut block: Block) {
 	// so will wait until a little later.
 }
 
-fn final_checks(_block: &Block) {
-	with_env(|e| {
-		assert_eq!(e.next_log_index, e.digest.logs.len());
-	});
-}
-
 /// Execute a given transaction.
 pub fn execute_transaction(utx: &UncheckedTransaction) {
 	// Verify the signature is good.
@@ -90,45 +84,23 @@ pub fn set_code(new: &[u8]) {
 	new.store(b"\0code");
 }
 
+fn final_checks(_block: &Block) {
+	with_env(|e| {
+		assert_eq!(e.next_log_index, e.digest.logs.len());
+	});
+}
+
 #[cfg(test)]
 mod tests {
 	use joiner::Joiner;
 	use function::Function;
 	use keyedvec::KeyedVec;
 	use slicable::Slicable;
-	use std::collections::HashMap;
-	use runtime_support::{NoError, with_externalities, Externalities};
-	use primitives::{AccountID, UncheckedTransaction, Transaction, Hashable};
+	use runtime_support::with_externalities;
+	use primitives::{UncheckedTransaction, Transaction};
 	use statichex::StaticHexInto;
 	use runtime::{system, staking};
-	use testing::HexDisplay;
-
-	#[derive(Debug, Default)]
-	struct TestExternalities {
-		storage: HashMap<Vec<u8>, Vec<u8>>,
-	}
-	impl Externalities for TestExternalities {
-		type Error = NoError;
-
-		fn storage(&self, key: &[u8]) -> Result<&[u8], NoError> {
-			Ok(self.storage.get(&key.to_vec()).map_or(&[] as &[u8], Vec::as_slice))
-		}
-
-		fn set_storage(&mut self, key: Vec<u8>, value: Vec<u8>) {
-			self.storage.insert(key, value);
-		}
-
-		fn chain_id(&self) -> u64 { 42 }
-	}
-
-	macro_rules! map {
-		($( $name:expr => $value:expr ),*) => (
-			vec![ $( ( $name, $value ) ),* ].into_iter().collect()
-		)
-	}
-
-	fn one() -> AccountID { "2f8c6129d816cf51c374bc7f08c3e63ed156cf78aefb4a6550d97b87997977ee".convert() }
-	fn two() -> AccountID { "d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a".convert() }
+	use testing::{TestExternalities, HexDisplay, one, two};
 
 	#[test]
 	fn staking_balance_transfer_dispatch_works() {
@@ -143,7 +115,7 @@ mod tests {
 			transaction: Transaction {
 				signed: one.clone(),
 				nonce: 0,
-				function: Function::StakingTransferStake,
+				function: Function::StakingTransferInactive,
 				input_data: vec![].join(&two).join(&69u64),
 			},
 			signature: "679fcf0a846b4224c84ecad7d91a26241c46d00cb53d6480a363274e8965ee34b0b80b4b2e3836d3d8f8f12c0c1aef7350af587d9aee3883561d11726068ac0a".convert(),
@@ -155,8 +127,8 @@ mod tests {
 
 		with_externalities(&mut t, || {
 			system::execute_transaction(&tx);
-			assert_eq!(staking::balance(&one), 42);
-			assert_eq!(staking::balance(&two), 69);
+			assert_eq!(staking::balance_inactive(&one), 42);
+			assert_eq!(staking::balance_inactive(&two), 69);
 		});
 	}
 }
diff --git a/substrate/wasm-runtime/polkadot/src/runtime/timestamp.rs b/substrate/wasm-runtime/polkadot/src/runtime/timestamp.rs
index 6d694c88ae..09c1d5bcbe 100644
--- a/substrate/wasm-runtime/polkadot/src/runtime/timestamp.rs
+++ b/substrate/wasm-runtime/polkadot/src/runtime/timestamp.rs
@@ -1,10 +1,36 @@
 use primitives::Timestamp;
 use storage::Storage;
 
-pub fn timestamp() -> Timestamp {
+pub fn get() -> Timestamp {
 	Storage::into(b"tim\0val")
 }
 
-pub fn set_timestamp(now: Timestamp) {
+pub fn set(now: Timestamp) {
 	now.store(b"tim\0val")
 }
+
+#[cfg(test)]
+mod tests {
+	use joiner::Joiner;
+	use function::Function;
+	use keyedvec::KeyedVec;
+	use slicable::Slicable;
+	use runtime_support::with_externalities;
+	use primitives::{UncheckedTransaction, Transaction};
+	use statichex::StaticHexInto;
+	use runtime::{system, timestamp};
+	use testing::{TestExternalities, HexDisplay, one, two};
+
+	#[test]
+	fn timestamp_works() {
+		let mut t = TestExternalities { storage: map![
+			b"tim\0val".to_vec() => vec![].join(&42u64)
+		], };
+
+		with_externalities(&mut t, || {
+			assert_eq!(timestamp::get(), 42);
+			timestamp::set(69);
+			assert_eq!(timestamp::get(), 69);
+		});
+	}
+}
diff --git a/substrate/wasm-runtime/polkadot/src/support/function.rs b/substrate/wasm-runtime/polkadot/src/support/function.rs
index 995ec3c459..45dcea876b 100644
--- a/substrate/wasm-runtime/polkadot/src/support/function.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/function.rs
@@ -1,6 +1,6 @@
-use runtime::{staking, session};
 use primitives::AccountID;
 use streamreader::StreamReader;
+use runtime::{staking, session, timestamp};
 
 /// The functions that a transaction can call (and be dispatched to).
 #[cfg_attr(test, derive(PartialEq, Debug))]
@@ -8,8 +8,9 @@ use streamreader::StreamReader;
 pub enum Function {
 	StakingStake,
 	StakingUnstake,
-	StakingTransferStake,
+	StakingTransferInactive,
 	SessionSetKey,
+	TimestampSet,
 }
 
 impl Function {
@@ -17,8 +18,9 @@ impl Function {
 		match value {
 			x if x == Function::StakingStake as u8 => Some(Function::StakingStake),
 			x if x == Function::StakingUnstake as u8 => Some(Function::StakingUnstake),
-			x if x == Function::StakingTransferStake as u8 => Some(Function::StakingTransferStake),
+			x if x == Function::StakingTransferInactive as u8 => Some(Function::StakingTransferInactive),
 			x if x == Function::SessionSetKey as u8 => Some(Function::SessionSetKey),
+			x if x == Function::TimestampSet as u8 => Some(Function::TimestampSet),
 			_ => None,
 		}
 	}
@@ -35,15 +37,19 @@ impl Function {
 			Function::StakingUnstake => {
 				staking::unstake(transactor);
 			}
-			Function::StakingTransferStake => {
+			Function::StakingTransferInactive => {
 				let dest = params.read().unwrap();
 				let value = params.read().unwrap();
-				staking::transfer_stake(transactor, &dest, value);
+				staking::transfer_inactive(transactor, &dest, value);
 			}
 			Function::SessionSetKey => {
 				let session = params.read().unwrap();
 				session::set_key(transactor, &session);
 			}
+			Function::TimestampSet => {
+				let t = params.read().unwrap();
+				timestamp::set(t);
+			}
 		}
 	}
 }
diff --git a/substrate/wasm-runtime/polkadot/src/support/mod.rs b/substrate/wasm-runtime/polkadot/src/support/mod.rs
index 732552effd..11cb23e997 100644
--- a/substrate/wasm-runtime/polkadot/src/support/mod.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/mod.rs
@@ -6,4 +6,5 @@ pub mod storage;
 #[cfg(test)]
 pub mod statichex;
 #[cfg(test)]
+#[macro_use]
 pub mod testing;
diff --git a/substrate/wasm-runtime/polkadot/src/support/primitives.rs b/substrate/wasm-runtime/polkadot/src/support/primitives.rs
index 4cf9dd9d32..ecac3fbbd4 100644
--- a/substrate/wasm-runtime/polkadot/src/support/primitives.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/primitives.rs
@@ -253,7 +253,7 @@ mod tests {
 		let tx = Transaction {
 			signed: one.clone(),
 			nonce: 69,
-			function: Function::StakingTransferStake,
+			function: Function::StakingTransferInactive,
 			input_data: Vec::new().join(&two).join(&69u64),
 		};
 		let serialised = tx.to_vec();
@@ -274,7 +274,7 @@ mod tests {
 		let tx = Transaction {
 			signed: one.clone(),
 			nonce: 69,
-			function: Function::StakingTransferStake,
+			function: Function::StakingTransferInactive,
 			input_data: Vec::new().join(&two).join(&69u64),
 		};
 		let data = [
@@ -344,7 +344,7 @@ mod tests {
 			transaction: Transaction {
 				signed: one.clone(),
 				nonce: 69,
-				function: Function::StakingTransferStake,
+				function: Function::StakingTransferInactive,
 				input_data: Vec::new().join(&two).join(&69u64),
 			},
 			signature: [1u8; 64],
@@ -408,7 +408,7 @@ mod tests {
 			transaction: Transaction {
 				signed: one.clone(),
 				nonce: 69,
-				function: Function::StakingTransferStake,
+				function: Function::StakingTransferInactive,
 				input_data: Vec::new().join(&two).join(&69u64),
 			},
 			signature: [1u8; 64],
diff --git a/substrate/wasm-runtime/polkadot/src/support/testing.rs b/substrate/wasm-runtime/polkadot/src/support/testing.rs
index 5338add635..a617405e79 100644
--- a/substrate/wasm-runtime/polkadot/src/support/testing.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/testing.rs
@@ -1,5 +1,7 @@
 use runtime_support::{NoError, Externalities};
 use std::collections::HashMap;
+use primitives::AccountID;
+use statichex::StaticHexInto;
 
 #[derive(Debug, Default)]
 pub struct TestExternalities {
@@ -20,6 +22,20 @@ impl Externalities for TestExternalities {
 	fn chain_id(&self) -> u64 { 42 }
 }
 
+#[macro_export]
+macro_rules! map {
+	($( $name:expr => $value:expr ),*) => (
+		vec![ $( ( $name, $value ) ),* ].into_iter().collect()
+	)
+}
+
+pub fn one() -> AccountID {
+	"2f8c6129d816cf51c374bc7f08c3e63ed156cf78aefb4a6550d97b87997977ee".convert()
+}
+pub fn two() -> AccountID {
+	"d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a".convert()
+}
+
 pub struct HexDisplay<'a>(&'a [u8]);
 
 impl<'a> HexDisplay<'a> {