diff --git a/substrate/executor/src/wasm_executor.rs b/substrate/executor/src/wasm_executor.rs
index cb2df774d9..41029424fa 100644
--- a/substrate/executor/src/wasm_executor.rs
+++ b/substrate/executor/src/wasm_executor.rs
@@ -136,8 +136,8 @@ impl_function_executor!(this: FunctionExecutor<'e, E>,
 			} else { 0 }
 		} else { 0 }
 	},
-	ext_deposit_log(_log_data: *const u8, _log_len: u32) => {
-		// TODO
+	ext_chain_id() -> u64 => {
+		42u64
 	}
 	=> <'e, E: Externalities + 'e>
 );
diff --git a/substrate/native-runtime/support/src/lib.rs b/substrate/native-runtime/support/src/lib.rs
index 795cae2ffd..9ec5f77bdd 100644
--- a/substrate/native-runtime/support/src/lib.rs
+++ b/substrate/native-runtime/support/src/lib.rs
@@ -68,6 +68,12 @@ pub fn set_storage(_key: &[u8], _value: &[u8]) {
 	);
 }
 
+/// The current relay chain identifier.
+pub fn chain_id() -> u64 {
+	// TODO: fetch from Externalities.
+	42u64
+}
+
 /// Execute the given closure with global function available whose functionality routes into the
 /// externalities `ext`. Forwards the value that the closure returns.
 pub fn with_externalities<R, F: FnOnce() -> R>(ext: &mut Externalities<Error=NoError>, f: F) -> R {
diff --git a/substrate/wasm-runtime/polkadot/src/consensus.rs b/substrate/wasm-runtime/polkadot/src/consensus.rs
index ef4d5a9856..add87a1808 100644
--- a/substrate/wasm-runtime/polkadot/src/consensus.rs
+++ b/substrate/wasm-runtime/polkadot/src/consensus.rs
@@ -1,3 +1,4 @@
+use runtime_support::Vec;
 use keyedvec::KeyedVec;
 use storage::Storage;
 use primitives::{AccountID, SessionKey, BlockNumber};
diff --git a/substrate/wasm-runtime/polkadot/src/lib.rs b/substrate/wasm-runtime/polkadot/src/lib.rs
index cc48d8caa6..680116b3d9 100644
--- a/substrate/wasm-runtime/polkadot/src/lib.rs
+++ b/substrate/wasm-runtime/polkadot/src/lib.rs
@@ -6,7 +6,9 @@ extern crate runtime_support;
 
 mod support;
 pub use support::{endiansensitive, streamreader, joiner, slicable, primitives, keyedvec, function,
-	environment, storage, testing};
+	environment, storage};
+#[cfg(test)]
+pub use support::testing;
 
 #[allow(unused)]
 mod system;
@@ -19,9 +21,12 @@ mod timestamp;
 
 use runtime_support::Vec;
 use slicable::Slicable;
-use primitives::{ChainID, Block, Transaction};
+use primitives::{Block, Transaction};
 
-// TODO: add keccak256 (or some better hashing scheme) & ECDSA-recover (or some better sig scheme)
+// TODO: add externals for:
+// - keccak256 (or some better hashing scheme)
+// - trie rooting
+// - ECDSA-recover (or some better sig scheme)
 
 pub fn execute_block(input: Vec<u8>) -> Vec<u8> {
 	system::execute_block(Block::from_slice(&input).unwrap())
@@ -32,9 +37,3 @@ pub fn execute_transaction(input: Vec<u8>) -> Vec<u8> {
 }
 
 impl_stubs!(execute_block, execute_transaction);
-
-/// The current relay chain identifier.
-pub fn chain_id() -> ChainID {
-	// TODO: retrieve from external
-	unimplemented!()
-}
diff --git a/substrate/wasm-runtime/polkadot/src/support/joiner.rs b/substrate/wasm-runtime/polkadot/src/support/joiner.rs
index 99b38dec57..817df8e4cb 100644
--- a/substrate/wasm-runtime/polkadot/src/support/joiner.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/joiner.rs
@@ -1,3 +1,4 @@
+use runtime_support::Vec;
 use slicable::Slicable;
 
 pub trait Joiner {
diff --git a/substrate/wasm-runtime/polkadot/src/support/keyedvec.rs b/substrate/wasm-runtime/polkadot/src/support/keyedvec.rs
index 3b0e595628..fcc410e582 100644
--- a/substrate/wasm-runtime/polkadot/src/support/keyedvec.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/keyedvec.rs
@@ -1,3 +1,4 @@
+use runtime_support::Vec;
 use primitives::AccountID;
 use slicable::Slicable;
 
diff --git a/substrate/wasm-runtime/polkadot/src/support/mod.rs b/substrate/wasm-runtime/polkadot/src/support/mod.rs
index dd381b1ad2..47b29194dc 100644
--- a/substrate/wasm-runtime/polkadot/src/support/mod.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/mod.rs
@@ -7,4 +7,6 @@ pub mod keyedvec;
 pub mod function;
 pub mod environment;
 pub mod storage;
+
+#[cfg(test)]
 pub mod testing;
diff --git a/substrate/wasm-runtime/polkadot/src/support/primitives.rs b/substrate/wasm-runtime/polkadot/src/support/primitives.rs
index 44d3bc4739..f1bd31cc66 100644
--- a/substrate/wasm-runtime/polkadot/src/support/primitives.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/primitives.rs
@@ -1,3 +1,4 @@
+use runtime_support::Vec;
 use streamreader::StreamReader;
 use joiner::Joiner;
 use slicable::{Slicable, NonTrivialSlicable};
@@ -62,7 +63,7 @@ impl Slicable for Transaction {
 	}
 
 	fn to_vec(&self) -> Vec<u8> {
-		vec![]
+		Vec::new()
 			.join(&self.signed)
 			.join(&(self.function as u8))
 			.join(&self.nonce)
@@ -84,7 +85,7 @@ impl<T: NonTrivialSlicable> Slicable for Vec<T> {
 	fn from_slice(value: &[u8]) -> Option<Self> {
 		let len = Self::size_of(&value[0..4])?;
 		let mut off = 4;
-		let mut r = vec![];
+		let mut r = Vec::new();
 		while off < len {
 			let element_len = T::size_of(&value[off..])?;
 			r.push(T::from_slice(&value[off..off + element_len])?);
@@ -100,7 +101,7 @@ impl<T: NonTrivialSlicable> Slicable for Vec<T> {
 	fn to_vec(&self) -> Vec<u8> {
 		let vecs = self.iter().map(Slicable::to_vec).collect::<Vec<_>>();
 		let len = vecs.iter().fold(0, |mut a, v| {a += v.len(); a});
-		let mut r = vec![].join(&(len as u32));
+		let mut r = Vec::new().join(&(len as u32));
 		vecs.iter().for_each(|v| r.extend_from_slice(v));
 		r
 	}
@@ -127,7 +128,7 @@ impl Slicable for Header {
 	}
 
 	fn to_vec(&self) -> Vec<u8> {
-		vec![]
+		Vec::new()
 			.join(&self.parent_hash)
 			.join(&self.number)
 			.join(&self.state_root)
@@ -156,7 +157,7 @@ impl Slicable for Block {
 	}
 
 	fn to_vec(&self) -> Vec<u8> {
-		vec![]
+		Vec::new()
 			.join(&self.header)
 			.join(&self.transactions)
 	}
@@ -181,7 +182,7 @@ mod tests {
 		let tx = Transaction {
 			signed: one.clone(),
 			function: Function::StakingTransferStake,
-			input_data: vec![].join(&two).join(&69u64),
+			input_data: Vec::new().join(&two).join(&69u64),
 			nonce: 69,
 		};
 		let serialised = tx.to_vec();
@@ -202,7 +203,7 @@ mod tests {
 		let tx = Transaction {
 			signed: one.clone(),
 			function: Function::StakingTransferStake,
-			input_data: vec![].join(&two).join(&69u64),
+			input_data: Vec::new().join(&two).join(&69u64),
 			nonce: 69,
 		};
 		let data = [
@@ -271,13 +272,13 @@ mod tests {
 		let tx1 = Transaction {
 			signed: one.clone(),
 			function: Function::StakingTransferStake,
-			input_data: vec![].join(&two).join(&69u64),
+			input_data: Vec::new().join(&two).join(&69u64),
 			nonce: 69,
 		};
 		let tx2 = Transaction {
 			signed: two.clone(),
 			function: Function::StakingStake,
-			input_data: vec![],
+			input_data: Vec::new(),
 			nonce: 42,
 		};
 		let h = Header {
@@ -327,13 +328,13 @@ mod tests {
 		let tx1 = Transaction {
 			signed: one.clone(),
 			function: Function::StakingTransferStake,
-			input_data: vec![].join(&two).join(&69u64),
+			input_data: Vec::new().join(&two).join(&69u64),
 			nonce: 69,
 		};
 		let tx2 = Transaction {
 			signed: two.clone(),
 			function: Function::StakingStake,
-			input_data: vec![],
+			input_data: Vec::new(),
 			nonce: 42,
 		};
 		let h = Header {
diff --git a/substrate/wasm-runtime/polkadot/src/support/slicable.rs b/substrate/wasm-runtime/polkadot/src/support/slicable.rs
index e220eb0f7d..939d1591ca 100644
--- a/substrate/wasm-runtime/polkadot/src/support/slicable.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/slicable.rs
@@ -59,7 +59,7 @@ impl Slicable for Vec<u8> {
 		unimplemented!();
 	}
 	fn to_vec(&self) -> Vec<u8> {
-		let mut r: Vec<u8> = vec![].join(&(self.len() as u32));
+		let mut r: Vec<u8> = Vec::new().join(&(self.len() as u32));
 		r.extend_from_slice(&self);
 		r
 	}
diff --git a/substrate/wasm-runtime/support/src/lib.rs b/substrate/wasm-runtime/support/src/lib.rs
index 9c64f1a72b..308ab6dd9e 100644
--- a/substrate/wasm-runtime/support/src/lib.rs
+++ b/substrate/wasm-runtime/support/src/lib.rs
@@ -10,6 +10,7 @@ pub use alloc::vec::Vec;
 pub use alloc::boxed::Box;
 pub use alloc::rc::Rc;
 pub use core::mem::{transmute, size_of, uninitialized, swap};
+pub use core::slice;
 pub use core::cell::{RefCell, Ref, RefMut};
 
 extern crate pwasm_libc;
@@ -27,7 +28,7 @@ extern "C" {
 	fn ext_set_storage(key_data: *const u8, key_len: u32, value_data: *const u8, value_len: u32);
 	fn ext_get_allocated_storage(key_data: *const u8, key_len: u32, written_out: *mut u32) -> *mut u8;
 	fn ext_get_storage_into(key_data: *const u8, key_len: u32, value_data: *mut u8, value_len: u32) -> u32;
-	fn ext_deposit_log(log_data: *const u8, log_len: u32);
+	fn ext_chain_id() -> u64;
 }
 
 pub fn storage(key: &[u8]) -> Vec<u8> {
@@ -64,11 +65,16 @@ pub fn set_storage(key: &[u8], value: &[u8]) {
 	}
 }
 
-pub fn deposit_log(log: &[u8]) {
+pub fn read_storage(key: &[u8], value_out: &mut [u8]) -> usize {
 	unsafe {
-		ext_deposit_log(
-			&log[0] as *const u8, log.len() as u32,
-		)
+		ext_get_storage_into(&key[0], key.len() as u32, &mut value_out[0], value_out.len() as u32) as usize
+	}
+}
+
+/// The current relay chain identifier.
+pub fn chain_id() -> u64 {
+	unsafe {
+		ext_chain_id()
 	}
 }
 
diff --git a/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.compact.wasm b/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.compact.wasm
index be2ae9b30e..658efc3738 100644
Binary files a/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.compact.wasm and b/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.compact.wasm differ
diff --git a/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.wasm b/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.wasm
index 228d1aaf0c..1d1c937b70 100644
Binary files a/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.wasm and b/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.wasm differ