diff --git a/substrate/core/cli/src/params.rs b/substrate/core/cli/src/params.rs
index 0f0617f859..c1135afb2e 100644
--- a/substrate/core/cli/src/params.rs
+++ b/substrate/core/cli/src/params.rs
@@ -263,9 +263,9 @@ pub struct ImportBlocksCmd {
 	)]
 	pub api_execution: ExecutionStrategy,
 
-	/// The maximum number of 64KB pages to ever allocate for Wasm execution. Don't alter this unless you know what you're doing.
-	#[structopt(long = "max-heap-pages", value_name = "COUNT")]
-	pub max_heap_pages: Option<u32>,
+	/// The default number of 64KB pages to allocate for Wasm execution. Don't alter this unless you know what you're doing.
+	#[structopt(long = "default-heap-pages", value_name = "COUNT")]
+	pub default_heap_pages: Option<u32>,
 
 	#[allow(missing_docs)]
 	#[structopt(flatten)]
diff --git a/substrate/core/client/src/genesis.rs b/substrate/core/client/src/genesis.rs
index 468d7137db..83f295ecc0 100644
--- a/substrate/core/client/src/genesis.rs
+++ b/substrate/core/client/src/genesis.rs
@@ -54,7 +54,7 @@ mod tests {
 	native_executor_instance!(Executor, test_client::runtime::api::dispatch, test_client::runtime::native_version, include_bytes!("../../test-runtime/wasm/target/wasm32-unknown-unknown/release/substrate_test_runtime.compact.wasm"));
 
 	fn executor() -> executor::NativeExecutor<Executor> {
-		NativeExecutionDispatch::new()
+		NativeExecutionDispatch::new(None)
 	}
 
 	fn construct_block(
@@ -207,7 +207,7 @@ mod tests {
 			&backend,
 			Some(&InMemoryChangesTrieStorage::new()),
 			&mut overlay,
-			&Executor::new(),
+			&Executor::new(None),
 			"Core_execute_block",
 			&b1data,
 			ExecutionStrategy::NativeWhenPossible,
diff --git a/substrate/core/client/src/light/call_executor.rs b/substrate/core/client/src/light/call_executor.rs
index 601cb0732f..f6ea6b32f2 100644
--- a/substrate/core/client/src/light/call_executor.rs
+++ b/substrate/core/client/src/light/call_executor.rs
@@ -450,7 +450,7 @@ mod tests {
 			).unwrap();
 
 			// check remote execution proof locally
-			let local_executor = test_client::LocalExecutor::new();
+			let local_executor = test_client::LocalExecutor::new(None);
 			let local_result = check_execution_proof(&local_executor, &RemoteCallRequest {
 				block: test_client::runtime::Hash::default(),
 				header: test_client::runtime::Header {
diff --git a/substrate/core/client/src/light/fetcher.rs b/substrate/core/client/src/light/fetcher.rs
index 49c7a5a5f2..1c1697eb34 100644
--- a/substrate/core/client/src/light/fetcher.rs
+++ b/substrate/core/client/src/light/fetcher.rs
@@ -456,7 +456,7 @@ pub mod tests {
 			None,
 			crate::backend::NewBlockState::Final,
 		).unwrap();
-		let local_executor = test_client::LocalExecutor::new();
+		let local_executor = test_client::LocalExecutor::new(None);
 		let local_checker = LightDataChecker::new(Arc::new(DummyBlockchain::new(DummyStorage::new())), local_executor);
 		(local_checker, remote_block_header, remote_read_proof, authorities_len)
 	}
@@ -482,7 +482,7 @@ pub mod tests {
 		if insert_cht {
 			local_storage.insert_cht_root(1, local_cht_root);
 		}
-		let local_executor = test_client::LocalExecutor::new();
+		let local_executor = test_client::LocalExecutor::new(None);
 		let local_checker = LightDataChecker::new(Arc::new(DummyBlockchain::new(DummyStorage::new())), local_executor);
 		(local_checker, local_cht_root, remote_block_header, remote_header_proof)
 	}
@@ -535,7 +535,7 @@ pub mod tests {
 		let (remote_client, local_roots, test_cases) = prepare_client_with_key_changes();
 		let local_checker = TestChecker::new(
 			Arc::new(DummyBlockchain::new(DummyStorage::new())),
-			test_client::LocalExecutor::new()
+			test_client::LocalExecutor::new(None)
 		);
 		let local_checker = &local_checker as &FetchChecker<Block>;
 		let max = remote_client.info().unwrap().chain.best_number;
@@ -603,7 +603,7 @@ pub mod tests {
 		local_storage.changes_tries_cht_roots.insert(0, local_cht_root);
 		let local_checker = TestChecker::new(
 			Arc::new(DummyBlockchain::new(local_storage)),
-			test_client::LocalExecutor::new()
+			test_client::LocalExecutor::new(None)
 		);
 
 		// check proof on local client
@@ -631,7 +631,7 @@ pub mod tests {
 		let (remote_client, local_roots, test_cases) = prepare_client_with_key_changes();
 		let local_checker = TestChecker::new(
 			Arc::new(DummyBlockchain::new(DummyStorage::new())),
-			test_client::LocalExecutor::new()
+			test_client::LocalExecutor::new(None)
 		);
 		let local_checker = &local_checker as &FetchChecker<Block>;
 		let max = remote_client.info().unwrap().chain.best_number;
@@ -712,7 +712,7 @@ pub mod tests {
 		// fails when changes trie CHT is missing from the local db
 		let local_checker = TestChecker::new(
 			Arc::new(DummyBlockchain::new(DummyStorage::new())),
-			test_client::LocalExecutor::new()
+			test_client::LocalExecutor::new(None)
 		);
 		assert!(local_checker.check_changes_tries_proof(4, &remote_proof.roots,
 			remote_proof.roots_proof.clone()).is_err());
@@ -722,7 +722,7 @@ pub mod tests {
 		local_storage.changes_tries_cht_roots.insert(0, local_cht_root);
 		let local_checker = TestChecker::new(
 			Arc::new(DummyBlockchain::new(local_storage)),
-			test_client::LocalExecutor::new()
+			test_client::LocalExecutor::new(None)
 		);
 		assert!(local_checker.check_changes_tries_proof(4, &remote_proof.roots, vec![]).is_err());
 	}
diff --git a/substrate/core/executor/src/native_executor.rs b/substrate/core/executor/src/native_executor.rs
index 2c2021179a..4ee58e4493 100644
--- a/substrate/core/executor/src/native_executor.rs
+++ b/substrate/core/executor/src/native_executor.rs
@@ -51,6 +51,7 @@ fn fetch_cached_runtime_version<'a, E: Externalities<Blake2Hasher>>(
 	wasm_executor: &WasmExecutor,
 	cache: &'a mut RefMut<CacheType>,
 	ext: &mut E,
+	default_heap_pages: Option<u64>,
 ) -> Result<(&'a WasmModuleInstanceRef, &'a Option<RuntimeVersion>)> {
 
 	let code_hash = match ext.storage_hash(well_known_keys::CODE) {
@@ -63,10 +64,10 @@ fn fetch_cached_runtime_version<'a, E: Externalities<Blake2Hasher>>(
 				Some(code) => code,
 				None => return RuntimePreproc::InvalidCode,
 			};
-			let heap_pages = match ext.storage(well_known_keys::HEAP_PAGES) {
-				Some(pages) => u64::decode(&mut &pages[..]).unwrap_or(DEFAULT_HEAP_PAGES),
-				None => DEFAULT_HEAP_PAGES,
-			};
+			let heap_pages = ext.storage(well_known_keys::HEAP_PAGES)
+				.and_then(|pages| u64::decode(&mut &pages[..]))
+				.or(default_heap_pages)
+				.unwrap_or(DEFAULT_HEAP_PAGES);
 			match WasmModule::from_buffer(code)
 				.map_err(|_| ErrorKind::InvalidCode(vec![]).into())
 				.and_then(|module| wasm_executor.prepare_module(ext, heap_pages as usize, &module))
@@ -125,7 +126,7 @@ pub trait NativeExecutionDispatch: Send + Sync {
 	fn native_version() -> NativeVersion;
 
 	/// Construct corresponding `NativeExecutor`
-	fn new() -> NativeExecutor<Self> where Self: Sized;
+	fn new(default_heap_pages: Option<u64>) -> NativeExecutor<Self> where Self: Sized;
 }
 
 /// A generic `CodeExecutor` implementation that uses a delegate to determine wasm code equivalence
@@ -138,15 +139,18 @@ pub struct NativeExecutor<D: NativeExecutionDispatch> {
 	fallback: WasmExecutor,
 	/// Native runtime version info.
 	native_version: NativeVersion,
+	/// The default number of 64KB pages to allocate for Wasm execution.
+	default_heap_pages: Option<u64>,
 }
 
 impl<D: NativeExecutionDispatch> NativeExecutor<D> {
 	/// Create new instance.
-	pub fn new() -> Self {
+	pub fn new(default_heap_pages: Option<u64>) -> Self {
 		NativeExecutor {
 			_dummy: Default::default(),
 			fallback: WasmExecutor::new(),
 			native_version: D::native_version(),
+			default_heap_pages,
 		}
 	}
 }
@@ -157,6 +161,7 @@ impl<D: NativeExecutionDispatch> Clone for NativeExecutor<D> {
 			_dummy: Default::default(),
 			fallback: self.fallback.clone(),
 			native_version: D::native_version(),
+			default_heap_pages: self.default_heap_pages,
 		}
 	}
 }
@@ -171,7 +176,8 @@ impl<D: NativeExecutionDispatch> RuntimeInfo for NativeExecutor<D> {
 		ext: &mut E,
 	) -> Option<RuntimeVersion> {
 		RUNTIMES_CACHE.with(|c|
-			fetch_cached_runtime_version(&self.fallback, &mut c.borrow_mut(), ext).ok()?.1.clone()
+			fetch_cached_runtime_version(&self.fallback, &mut c.borrow_mut(), ext, self.default_heap_pages)
+				.ok()?.1.clone()
 		)
 	}
 }
@@ -194,9 +200,10 @@ impl<D: NativeExecutionDispatch> CodeExecutor<Blake2Hasher> for NativeExecutor<D
 	) -> (Result<NativeOrEncoded<R>>, bool) {
 		RUNTIMES_CACHE.with(|c| {
 			let mut c = c.borrow_mut();
-			let (module, onchain_version) = match fetch_cached_runtime_version(&self.fallback, &mut c, ext) {
-				Ok((module, onchain_version)) => (module, onchain_version),
-				Err(e) => return (Err(e), false),
+			let (module, onchain_version) = match fetch_cached_runtime_version(
+				&self.fallback, &mut c, ext, self.default_heap_pages) {
+					Ok((module, onchain_version)) => (module, onchain_version),
+					Err(e) => return (Err(e), false),
 			};
 			match (
 				use_native,
@@ -281,8 +288,8 @@ macro_rules! native_executor_instance {
 				$version()
 			}
 
-			fn new() -> $crate::NativeExecutor<$name> {
-				$crate::NativeExecutor::new()
+			fn new(default_heap_pages: Option<u64>) -> $crate::NativeExecutor<$name> {
+				$crate::NativeExecutor::new(default_heap_pages)
 			}
 		}
 	}
diff --git a/substrate/core/service/src/config.rs b/substrate/core/service/src/config.rs
index 636b555617..fa02561dfe 100644
--- a/substrate/core/service/src/config.rs
+++ b/substrate/core/service/src/config.rs
@@ -67,6 +67,8 @@ pub struct Configuration<C, G: Serialize + DeserializeOwned + BuildStorage> {
 	pub rpc_ws: Option<SocketAddr>,
 	/// Telemetry service URL. `None` if disabled.
 	pub telemetry_url: Option<String>,
+	/// The default number of 64KB pages to allocate for Wasm execution
+	pub default_heap_pages: Option<u64>,
 }
 
 impl<C: Default, G: Serialize + DeserializeOwned + BuildStorage> Configuration<C, G> {
@@ -92,6 +94,7 @@ impl<C: Default, G: Serialize + DeserializeOwned + BuildStorage> Configuration<C
 			rpc_http: None,
 			rpc_ws: None,
 			telemetry_url: None,
+			default_heap_pages: None,
 		};
 		configuration.network.boot_nodes = configuration.chain_spec.boot_nodes().to_vec();
 		configuration.telemetry_url = configuration.chain_spec.telemetry_url().map(str::to_owned);
diff --git a/substrate/core/service/src/lib.rs b/substrate/core/service/src/lib.rs
index abffc2b74c..f4c9463ab3 100644
--- a/substrate/core/service/src/lib.rs
+++ b/substrate/core/service/src/lib.rs
@@ -113,7 +113,7 @@ pub struct Service<Components: components::Components> {
 pub fn new_client<Factory: components::ServiceFactory>(config: &FactoryFullConfiguration<Factory>)
 	-> Result<Arc<ComponentClient<components::FullComponents<Factory>>>, error::Error>
 {
-	let executor = NativeExecutor::new();
+	let executor = NativeExecutor::new(config.default_heap_pages);
 	let (client, _) = components::FullComponents::<Factory>::build_client(
 		config,
 		executor,
@@ -132,7 +132,7 @@ impl<Components: components::Components> Service<Components> {
 		let (signal, exit) = ::exit_future::signal();
 
 		// Create client
-		let executor = NativeExecutor::new();
+		let executor = NativeExecutor::new(config.default_heap_pages);
 
 		let mut keystore = Keystore::open(config.keystore_path.as_str().into())?;
 
diff --git a/substrate/core/service/test/src/lib.rs b/substrate/core/service/test/src/lib.rs
index 97ad89bcdb..db38fa142d 100644
--- a/substrate/core/service/test/src/lib.rs
+++ b/substrate/core/service/test/src/lib.rs
@@ -135,6 +135,7 @@ fn node_config<F: ServiceFactory> (
 		rpc_http: None,
 		rpc_ws: None,
 		telemetry_url: None,
+		default_heap_pages: None,
 	}
 }
 
diff --git a/substrate/core/test-client/src/lib.rs b/substrate/core/test-client/src/lib.rs
index eec5770fc1..fe5f8d4478 100644
--- a/substrate/core/test-client/src/lib.rs
+++ b/substrate/core/test-client/src/lib.rs
@@ -76,7 +76,7 @@ pub fn new_with_api_execution_strat(
 	api_execution_strategy: ExecutionStrategy
 ) -> client::Client<Backend, Executor, runtime::Block, runtime::RuntimeApi> {
 	let backend = Arc::new(Backend::new());
-	let executor = NativeExecutor::new();
+	let executor = NativeExecutor::new(None);
 	let executor = LocalCallExecutor::new(backend.clone(), executor);
 
 	client::Client::new(
@@ -95,7 +95,7 @@ pub fn new_with_changes_trie()
 	new_with_backend(Arc::new(Backend::new()), true)
 }
 
-/// Creates new client instance used for tests with an explicitely provided backend.
+/// Creates new client instance used for tests with an explicitly provided backend.
 /// This is useful for testing backend implementations.
 pub fn new_with_backend<B>(
 	backend: Arc<B>,
@@ -107,7 +107,7 @@ pub fn new_with_backend<B>(
 	runtime::RuntimeApi
 > where B: backend::LocalBackend<runtime::Block, Blake2Hasher>
 {
-	let executor = NativeExecutor::new();
+	let executor = NativeExecutor::new(None);
 	client::new_with_backend(backend, executor, genesis_storage(support_changes_trie)).unwrap()
 }
 
diff --git a/substrate/node/executor/src/lib.rs b/substrate/node/executor/src/lib.rs
index d98a8f32cc..44fd6efa68 100644
--- a/substrate/node/executor/src/lib.rs
+++ b/substrate/node/executor/src/lib.rs
@@ -101,7 +101,7 @@ mod tests {
 	}
 
 	fn executor() -> ::substrate_executor::NativeExecutor<Executor> {
-		::substrate_executor::NativeExecutor::new()
+		::substrate_executor::NativeExecutor::new(None)
 	}
 
 	#[test]
@@ -729,7 +729,7 @@ mod tests {
 	fn native_big_block_import_succeeds() {
 		let mut t = new_test_ext(COMPACT_CODE, false);
 
-		Executor::new().call::<_, NeverNativeValue, fn() -> _>(
+		Executor::new(None).call::<_, NeverNativeValue, fn() -> _>(
 			&mut t,
 			"Core_execute_block",
 			&block1big().0,
@@ -743,7 +743,7 @@ mod tests {
 		let mut t = new_test_ext(COMPACT_CODE, false);
 
 		assert!(
-			Executor::new().call::<_, NeverNativeValue, fn() -> _>(
+			Executor::new(None).call::<_, NeverNativeValue, fn() -> _>(
 				&mut t,
 				"Core_execute_block",
 				&block1big().0,
@@ -805,7 +805,7 @@ mod tests {
 	#[test]
 	fn full_native_block_import_works_with_changes_trie() {
 		let mut t = new_test_ext(COMPACT_CODE, true);
-		Executor::new().call::<_, NeverNativeValue, fn() -> _>(
+		Executor::new(None).call::<_, NeverNativeValue, fn() -> _>(
 			&mut t,
 			"Core_execute_block",
 			&block1(true).0,