diff --git a/substrate/Cargo.lock b/substrate/Cargo.lock
index 1595bc0272..a7047446eb 100644
--- a/substrate/Cargo.lock
+++ b/substrate/Cargo.lock
@@ -498,6 +498,11 @@ dependencies = [
  "libc 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "memcmp"
+version = "0.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "memorydb"
 version = "0.1.1"
@@ -726,6 +731,7 @@ dependencies = [
  "assert_matches 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "error-chain 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "memcmp 0.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "native-runtime 0.1.0",
  "parity-wasm 0.15.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "polkadot-primitives 0.1.0",
@@ -1333,6 +1339,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum libc 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)" = "5ba3df4dcb460b9dfbd070d41c94c19209620c191b0340b929ce748a2bcd42d2"
 "checksum log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "880f77541efa6e5cc74e76910c9884d9859683118839d6a1dc3b11e63512565b"
 "checksum memchr 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "148fab2e51b4f1cfc66da2a7c32981d1d3c083a803978268bb11fe4b86925e7a"
+"checksum memcmp 0.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "9a1b44fee357b6a05a9e22554ded6c1bbe57844b58190295257ac0ad4c5944e1"
 "checksum memorydb 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "013b7e4c5e10c764936ebc6bd3662d8e3c92292d267bf6a42ef3f5cad9c793ee"
 "checksum mime 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e2e00e17be181010a91dbfefb01660b17311059dc8c7f48b9017677721e732bd"
 "checksum mio 0.6.11 (registry+https://github.com/rust-lang/crates.io-index)" = "0e8411968194c7b139e9105bc4ae7db0bae232af087147e72f0616ebf5fdb9cb"
diff --git a/substrate/executor/Cargo.toml b/substrate/executor/Cargo.toml
index dbdef883cc..6164bb1c51 100644
--- a/substrate/executor/Cargo.toml
+++ b/substrate/executor/Cargo.toml
@@ -15,6 +15,7 @@ byteorder = "1.1"
 rustc-hex = "1.0.0"
 native-runtime = { path = "../native-runtime", version = "0.1" }
 runtime-support = { path = "../native-runtime/support", version = "0.1" }
+memcmp = { version = "0.0.6" }
 
 [dev-dependencies]
 assert_matches = "1.1"
diff --git a/substrate/executor/src/lib.rs b/substrate/executor/src/lib.rs
index 56c39e5b49..17b1ec9025 100644
--- a/substrate/executor/src/lib.rs
+++ b/substrate/executor/src/lib.rs
@@ -34,8 +34,10 @@ extern crate serde;
 extern crate parity_wasm;
 extern crate byteorder;
 extern crate rustc_hex;
+#[macro_use]
 extern crate native_runtime;
 extern crate runtime_support;
+extern crate memcmp;
 
 #[macro_use]
 extern crate error_chain;
diff --git a/substrate/executor/src/native_executor.rs b/substrate/executor/src/native_executor.rs
index 28146a46ea..e195e8f8d7 100644
--- a/substrate/executor/src/native_executor.rs
+++ b/substrate/executor/src/native_executor.rs
@@ -33,3 +33,53 @@ impl CodeExecutor for NativeExecutor {
 		}
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use primitives::twox_128;
+	use native_runtime::testing::{TestExternalities, one, two};
+	use native_runtime::statichex::StaticHexInto;
+	use native_runtime::keyedvec::KeyedVec;
+	use native_runtime::runtime::staking::balance;
+
+	fn tx() -> Vec<u8> { "679fcf0a846b4224c84ecad7d91a26241c46d00cb53d6480a363274e8965ee34b0b80b4b2e3836d3d8f8f12c0c1aef7350af587d9aee3883561d11726068ac0a2f8c6129d816cf51c374bc7f08c3e63ed156cf78aefb4a6550d97b87997977ee00000000000000000228000000d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a4500000000000000".convert() }
+
+	#[test]
+	fn execution_with_native_equivalent_code_runs_native_ok() {
+		let one = one();
+		let two = two();
+
+		let mut t = TestExternalities { storage: map![
+			twox_128(&one.to_keyed_vec(b"sta:bal:")).to_vec() => vec![111u8, 0, 0, 0, 0, 0, 0, 0]
+		], };
+
+		let native_equivalent_code = include_bytes!("../../wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.compact.wasm");
+		NativeExecutor.call(&mut t, &native_equivalent_code[..], "execute_transaction", &CallData(tx()));
+
+		runtime_support::with_externalities(&mut t, || {
+			assert_eq!(balance(&one), 42);
+			assert_eq!(balance(&two), 69);
+		});
+	}
+
+	#[test]
+	fn execution_with_foreign_code_runs_wasm_ok() {
+		let one = one();
+		let two = two();
+
+		let mut t = TestExternalities { storage: map![
+			twox_128(&one.to_keyed_vec(b"sta:bal:")).to_vec() => vec![111u8, 0, 0, 0, 0, 0, 0, 0]
+		], };
+
+		let mut foreign_code = include_bytes!("../../wasm-runtime/target/wasm32-unknown-unknown/release/runtime_polkadot.wasm");
+		NativeExecutor.call(&mut t, &foreign_code[..], "execute_transaction", &CallData(tx()));
+
+		runtime_support::with_externalities(&mut t, || {
+			assert_eq!(balance(&one), 42);
+			assert_eq!(balance(&two), 69);
+		});
+	}
+
+	// TODO: test panics.
+}
diff --git a/substrate/executor/src/wasm_executor.rs b/substrate/executor/src/wasm_executor.rs
index 561e557ad9..f7d922d6fb 100644
--- a/substrate/executor/src/wasm_executor.rs
+++ b/substrate/executor/src/wasm_executor.rs
@@ -87,6 +87,15 @@ impl_function_executor!(this: FunctionExecutor<'e, E>,
 	ext_print_num(number: u64) => {
 		println!("Runtime: {}", number);
 	},
+	ext_memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 => {
+		if let (Ok(sl1), Ok(sl2))
+			= (this.memory.get(s1, n as usize), this.memory.get(s2, n as usize)) {
+			use memcmp::Memcmp;
+			(&sl1).memcmp(&sl2) as i32
+		} else {
+			0
+		}
+	},
 	ext_memcpy(dest: *mut u8, src: *const u8, count: usize) -> *mut u8 => {
 		let _ = this.memory.copy_nonoverlapping(src as usize, dest as usize, count as usize);
 		println!("memcpy {} from {}, {} bytes", dest, src, count);
@@ -242,22 +251,7 @@ mod tests {
 	use super::*;
 	use rustc_hex::FromHex;
 	use state_machine::ExternalitiesError;
-
-	#[derive(Debug, Default)]
-	struct TestExternalities {
-		storage: HashMap<Vec<u8>, Vec<u8>>,
-	}
-	impl Externalities for TestExternalities {
-		fn storage(&self, key: &[u8]) -> ::std::result::Result<&[u8], ExternalitiesError> {
-			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 }
-	}
+	use native_runtime::testing::{TestExternalities, one, two};
 
 	#[test]
 	fn storage_should_work() {
diff --git a/substrate/wasm-runtime/polkadot/src/lib.rs b/substrate/wasm-runtime/polkadot/src/lib.rs
index 3d52aa589f..1134d974a7 100644
--- a/substrate/wasm-runtime/polkadot/src/lib.rs
+++ b/substrate/wasm-runtime/polkadot/src/lib.rs
@@ -22,22 +22,28 @@
 #[macro_use]
 extern crate runtime_support;
 
-#[cfg(test)]
+#[cfg(feature = "with-std")]
 extern crate rustc_hex;
 
 mod codec;
 #[macro_use]
 mod support;
-mod runtime;
+pub mod runtime;
 pub use codec::{endiansensitive, streamreader, joiner, slicable, keyedvec};
 pub use support::{primitives, function, proposal, environment, storable};
-#[cfg(test)]
+#[cfg(feature = "with-std")]
 pub use support::{testing, statichex};
 
 use runtime_support::prelude::*;
 use slicable::Slicable;
 use primitives::{Block, UncheckedTransaction};
 
+/// A simple test.
+pub fn simple_test(input: &[u8]) -> Vec<u8> {
+	println!("Executing block");
+	Vec::new()
+}
+
 /// Execute a block, with `input` being the canonical serialisation of the block. Returns the
 /// empty vector.
 pub fn execute_block(input: &[u8]) -> Vec<u8> {
@@ -47,7 +53,10 @@ pub fn execute_block(input: &[u8]) -> Vec<u8> {
 
 /// Execute a given, serialised, transaction. Returns the empty vector.
 pub fn execute_transaction(input: &[u8]) -> Vec<u8> {
-	runtime::system::execute_transaction(&UncheckedTransaction::from_slice(input).unwrap());
+	println!("Deserialising... {:?}", input);
+	let utx = UncheckedTransaction::from_slice(input).unwrap();
+	println!("Forwarding... {:?}", utx);
+	runtime::system::execute_transaction(&utx);
 	Vec::new()
 }
 
diff --git a/substrate/wasm-runtime/polkadot/src/runtime/system.rs b/substrate/wasm-runtime/polkadot/src/runtime/system.rs
index 042d1af2d7..70348574b1 100644
--- a/substrate/wasm-runtime/polkadot/src/runtime/system.rs
+++ b/substrate/wasm-runtime/polkadot/src/runtime/system.rs
@@ -84,6 +84,7 @@ pub fn execute_block(mut block: Block) {
 
 /// Execute a given transaction.
 pub fn execute_transaction(utx: &UncheckedTransaction) {
+	println!("Executing...");
 	// Verify the signature is good.
 	assert!(utx.ed25519_verify(), "All transactions should be properly signed");
 
@@ -97,6 +98,8 @@ pub fn execute_transaction(utx: &UncheckedTransaction) {
 	// increment nonce in storage
 	(expected_nonce + 1).store(&nonce_key);
 
+	println!("Dispatching...");
+
 	// decode parameters and dispatch
 	tx.function.dispatch(&tx.signed, &tx.input_data);
 }
diff --git a/substrate/wasm-runtime/polkadot/src/support/function.rs b/substrate/wasm-runtime/polkadot/src/support/function.rs
index dd54ba1080..875bb98326 100644
--- a/substrate/wasm-runtime/polkadot/src/support/function.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/function.rs
@@ -21,8 +21,8 @@ use streamreader::StreamReader;
 use runtime::{staking, session, timestamp, governance};
 
 /// Public functions that can be dispatched to.
-#[cfg_attr(test, derive(PartialEq, Debug))]
 #[derive(Clone, Copy)]
+#[cfg_attr(feature = "with-std", derive(PartialEq, Debug))]
 pub enum Function {
 	StakingStake,
 	StakingUnstake,
diff --git a/substrate/wasm-runtime/polkadot/src/support/mod.rs b/substrate/wasm-runtime/polkadot/src/support/mod.rs
index 384909d019..3730483b25 100644
--- a/substrate/wasm-runtime/polkadot/src/support/mod.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/mod.rs
@@ -22,8 +22,8 @@ pub mod proposal;
 pub mod environment;
 pub mod storable;
 
-#[cfg(test)]
+#[cfg(feature = "with-std")]
 pub mod statichex;
-#[cfg(test)]
 #[macro_use]
+#[cfg(feature = "with-std")]
 pub mod testing;
diff --git a/substrate/wasm-runtime/polkadot/src/support/primitives.rs b/substrate/wasm-runtime/polkadot/src/support/primitives.rs
index fe5bb2ebbd..48fa91dd79 100644
--- a/substrate/wasm-runtime/polkadot/src/support/primitives.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/primitives.rs
@@ -23,7 +23,7 @@ use slicable::{Slicable, NonTrivialSlicable};
 use function::Function;
 use runtime_support::{mem, blake2_256, twox_128, twox_256, ed25519_verify};
 
-#[cfg(test)]
+#[cfg(feature = "with-std")]
 use std::fmt;
 
 /// The Ed25519 pubkey that identifies an account.
@@ -51,7 +51,7 @@ pub type TxOrder = u64;
 pub type Hash = [u8; 32];
 
 #[derive(Clone, Default)]
-#[cfg_attr(test, derive(PartialEq, Debug))]
+#[cfg_attr(feature = "with-std", derive(PartialEq, Debug))]
 /// The digest of a block, useful for light-clients.
 pub struct Digest {
 	/// All logs that have happened in the block.
@@ -59,7 +59,7 @@ pub struct Digest {
 }
 
 #[derive(Clone)]
-#[cfg_attr(test, derive(PartialEq, Debug))]
+#[cfg_attr(feature = "with-std", derive(PartialEq, Debug))]
 /// The header for a block.
 pub struct Header {
 	/// The parent block's "hash" (actually the Blake2-256 hash of its serialised header).
@@ -108,8 +108,8 @@ impl Slicable for Header {
 
 impl NonTrivialSlicable for Header {}
 
-#[cfg_attr(test, derive(PartialEq, Debug))]
 /// A vetted and verified transaction from the external world.
+#[cfg_attr(feature = "with-std", derive(PartialEq, Debug))]
 pub struct Transaction {
 	/// Who signed it (note this is not a signature).
 	pub signed: AccountID,
@@ -187,14 +187,14 @@ impl UncheckedTransaction {
 	}
 }
 
-#[cfg(test)]
+#[cfg(feature = "with-std")]
 impl PartialEq for UncheckedTransaction {
 	fn eq(&self, other: &Self) -> bool {
 		self.signature.iter().eq(other.signature.iter()) && self.transaction == other.transaction
 	}
 }
 
-#[cfg(test)]
+#[cfg(feature = "with-std")]
 impl fmt::Debug for UncheckedTransaction {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		write!(f, "UncheckedTransaction({:?})", self.transaction)
@@ -229,8 +229,8 @@ impl Slicable for UncheckedTransaction {
 
 impl NonTrivialSlicable for UncheckedTransaction {}
 
-#[cfg_attr(test, derive(PartialEq, Debug))]
 /// A Polkadot relay chain block.
+#[cfg_attr(feature = "with-std", derive(PartialEq, Debug))]
 pub struct Block {
 	/// The header of the block.
 	pub header: Header,
diff --git a/substrate/wasm-runtime/polkadot/src/support/proposal.rs b/substrate/wasm-runtime/polkadot/src/support/proposal.rs
index ec02e32dfb..663692a4f7 100644
--- a/substrate/wasm-runtime/polkadot/src/support/proposal.rs
+++ b/substrate/wasm-runtime/polkadot/src/support/proposal.rs
@@ -25,8 +25,8 @@ use streamreader::StreamReader;
 use runtime::{system, governance, staking, session};
 
 /// Internal functions that can be dispatched to.
-#[cfg_attr(test, derive(PartialEq, Debug))]
 #[derive(Clone, Copy)]
+#[cfg_attr(feature = "with-std", derive(PartialEq, Debug))]
 pub enum InternalFunction {
 	SystemSetCode,
 	StakingSetSessionsPerEra,
@@ -52,7 +52,7 @@ impl InternalFunction {
 }
 
 /// An internal function.
-#[cfg_attr(test, derive(PartialEq, Debug))]
+#[cfg_attr(feature = "with-std", derive(PartialEq, Debug))]
 pub struct Proposal {
 	/// The priviledged function to call.
 	pub function: InternalFunction,
diff --git a/substrate/wasm-runtime/pwasm-libc/src/lib.rs b/substrate/wasm-runtime/pwasm-libc/src/lib.rs
index eed597e73b..0c2fd43fc6 100644
--- a/substrate/wasm-runtime/pwasm-libc/src/lib.rs
+++ b/substrate/wasm-runtime/pwasm-libc/src/lib.rs
@@ -8,6 +8,7 @@ extern "C" {
 	fn ext_memcpy(dest: *mut u8, src: *const u8, n: usize) -> *mut u8;
 	fn ext_memmove(dest: *mut u8, src: *const u8, n: usize) -> *mut u8;
 	fn ext_memset(dest: *mut u8, c: i32, n: usize) -> *mut u8;
+	fn ext_memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32;
 	fn ext_malloc(size: usize) -> *mut u8;
 	fn ext_free(ptr: *mut u8);
 }
@@ -21,6 +22,12 @@ pub unsafe extern "C" fn memcpy(dest: *mut u8, src: *const u8, n: usize) -> *mut
 	ext_memcpy(dest, src, n)
 }
 
+/// memcpy extern
+#[no_mangle]
+pub unsafe extern "C" fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 {
+	ext_memcmp(s1, s2, n)
+}
+
 /// memmove extern
 #[no_mangle]
 pub unsafe extern "C" fn memmove(dest: *mut u8, src: *const u8, n: usize) -> *mut u8 {
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 84f6597460..688c7bcdb8 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 d758dcbb60..861eb4c608 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
diff --git a/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_test.wasm b/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_test.wasm
index 1b822803e0..1b9dc8a1cd 100644
Binary files a/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_test.wasm and b/substrate/wasm-runtime/target/wasm32-unknown-unknown/release/runtime_test.wasm differ