diff --git a/substrate/core/client/src/block_builder/block_builder.rs b/substrate/core/client/src/block_builder/block_builder.rs
index 7d5b867e3a..cb67db5adf 100644
--- a/substrate/core/client/src/block_builder/block_builder.rs
+++ b/substrate/core/client/src/block_builder/block_builder.rs
@@ -39,7 +39,7 @@ impl<'a, Block, A> BlockBuilder<'a, Block, A>
 where
 	Block: BlockT<Hash=H256>,
 	A: ProvideRuntimeApi + HeaderBackend<Block> + 'a,
-	A::Api: BlockBuilderApi<Block>,
+	A::Api: BlockBuilderApi<Block> + Core<Block>,
 {
 	/// Create a new instance of builder from the given client, building on the latest block.
 	pub fn new(api: &'a A) -> error::Result<Self> {
@@ -84,7 +84,7 @@ where
 			block_id: &BlockId<Block>,
 			xt: Block::Extrinsic,
 			extrinsics: &mut Vec<Block::Extrinsic>
-		) -> error::Result<()> where T: BlockBuilderApi<Block> {
+		) -> error::Result<()> where T: BlockBuilderApi<Block> + Core<Block> {
 			api.map_api_result(|api| {
 				match api.apply_extrinsic(block_id, &xt)? {
 					Ok(ApplyOutcome::Success) | Ok(ApplyOutcome::Fail) => {
diff --git a/substrate/core/client/src/client.rs b/substrate/core/client/src/client.rs
index 03cefca49e..df03cc8e0e 100644
--- a/substrate/core/client/src/client.rs
+++ b/substrate/core/client/src/client.rs
@@ -547,7 +547,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		&self
 	) -> error::Result<block_builder::BlockBuilder<Block, Self>> where
 		E: Clone + Send + Sync,
-		RA: BlockBuilderAPI<Block>
+		RA: BlockBuilderAPI<Block> + CoreAPI<Block>,
 	{
 		block_builder::BlockBuilder::new(self)
 	}
@@ -557,7 +557,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		&self, parent: &BlockId<Block>
 	) -> error::Result<block_builder::BlockBuilder<Block, Self>> where
 		E: Clone + Send + Sync,
-		RA: BlockBuilderAPI<Block>
+		RA: BlockBuilderAPI<Block> + CoreAPI<Block>,
 	{
 		block_builder::BlockBuilder::at_block(parent, &self)
 	}
@@ -568,7 +568,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		at: Block::Hash,
 		body: &Option<Vec<Block::Extrinsic>>
 	) -> error::Result<Vec<TransactionTag>> where
-		RA: TaggedTransactionQueue<Block>,
+		RA: TaggedTransactionQueue<Block> + CoreAPI<Block>,
 		E: CallExecutor<Block, Blake2Hasher> + Send + Sync + Clone,
 	{
 		let id = BlockId::Hash(at);
@@ -604,7 +604,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		finalized: bool,
 		aux: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 	) -> error::Result<ImportResult> where
-		RA: TaggedTransactionQueue<Block>,
+		RA: TaggedTransactionQueue<Block> + CoreAPI<Block>,
 		E: CallExecutor<Block, Blake2Hasher> + Send + Sync + Clone,
 	{
 		let parent_hash = import_headers.post().parent_hash().clone();
@@ -1058,7 +1058,7 @@ impl<B, E, Block, RA> consensus::BlockImport<Block> for Client<B, E, Block, RA>
 	B: backend::Backend<Block, Blake2Hasher>,
 	E: CallExecutor<Block, Blake2Hasher> + Clone + Send + Sync,
 	Block: BlockT<Hash=H256>,
-	RA: TaggedTransactionQueue<Block>
+	RA: TaggedTransactionQueue<Block> + CoreAPI<Block>,
 {
 	type Error = Error;
 
diff --git a/substrate/core/client/src/runtime_api/macros.rs b/substrate/core/client/src/runtime_api/macros.rs
index b58f2143c8..ad13d8b265 100644
--- a/substrate/core/client/src/runtime_api/macros.rs
+++ b/substrate/core/client/src/runtime_api/macros.rs
@@ -347,7 +347,7 @@ macro_rules! decl_runtime_apis {
 	) => {
 		$( #[$attr] )*
 		#[cfg(feature = "std")]
-		pub trait $name < $( $generic_param_parsed $( : $generic_bound_parsed )* ),* > : $crate::runtime_api::Core<Block> {
+		pub trait $name < $( $generic_param_parsed $( : $generic_bound_parsed )* ),* > {
 			$( type $client_generic_param $( : $client_generic_bound )*; )*
 
 			$(
diff --git a/substrate/core/client/src/runtime_api/mod.rs b/substrate/core/client/src/runtime_api/mod.rs
index e151718360..fd3bc5f172 100644
--- a/substrate/core/client/src/runtime_api/mod.rs
+++ b/substrate/core/client/src/runtime_api/mod.rs
@@ -23,7 +23,7 @@ pub use state_machine::OverlayedChanges;
 #[doc(hidden)]
 pub use runtime_primitives::{traits::Block as BlockT, generic::BlockId};
 #[cfg(feature = "std")]
-use runtime_primitives::traits::ApiRef;
+pub use runtime_primitives::traits::ApiRef;
 pub use runtime_version::ApiId;
 #[doc(hidden)]
 pub use rstd::slice;
diff --git a/substrate/core/finality-grandpa/src/lib.rs b/substrate/core/finality-grandpa/src/lib.rs
index 60f56776da..7aa377410f 100644
--- a/substrate/core/finality-grandpa/src/lib.rs
+++ b/substrate/core/finality-grandpa/src/lib.rs
@@ -84,7 +84,7 @@ use futures::stream::Fuse;
 use futures::sync::mpsc;
 use client::{Client, error::Error as ClientError, ImportNotifications, backend::Backend, CallExecutor};
 use client::blockchain::HeaderBackend;
-use client::runtime_api::TaggedTransactionQueue;
+use client::runtime_api::{Core as CoreAPI, TaggedTransactionQueue};
 use codec::{Encode, Decode};
 use consensus_common::{BlockImport, ImportBlock, ImportResult};
 use runtime_primitives::traits::{
@@ -775,16 +775,16 @@ impl<B, E, Block: BlockT<Hash=H256>, N, RA> voter::Environment<Block::Hash, Numb
 /// This scans each imported block for signals of changing authority set.
 /// When using GRANDPA, the block import worker should be using this block import
 /// object.
-pub struct GrandpaBlockImport<B, E, Block: BlockT<Hash=H256>, RA> {
-	inner: Arc<Client<B, E, Block, RA>>,
+pub struct GrandpaBlockImport<Import, Api, Block: BlockT> {
+	import: Import,
 	authority_set: SharedAuthoritySet<Block::Hash, NumberFor<Block>>,
+	api: Api,
 }
 
-impl<B, E, Block: BlockT<Hash=H256>, RA> BlockImport<Block> for GrandpaBlockImport<B, E, Block, RA> where
-	B: Backend<Block, Blake2Hasher> + 'static,
-	E: CallExecutor<Block, Blake2Hasher> + 'static + Clone + Send + Sync,
-	DigestFor<Block>: Encode,
-	RA: GrandpaApi<Block> + TaggedTransactionQueue<Block>,
+impl<Import, Api, Block: BlockT<Hash=H256>> BlockImport<Block> for GrandpaBlockImport<Import, Api, Block> where
+	Import: BlockImport<Block>,
+	Api: ProvideRuntimeApi,
+	Api::Api: GrandpaApi<Block>,
 {
 	type Error = ClientError;
 
@@ -793,7 +793,7 @@ impl<B, E, Block: BlockT<Hash=H256>, RA> BlockImport<Block> for GrandpaBlockImpo
 	{
 		use authorities::PendingChange;
 
-		let maybe_change = self.inner.runtime_api().grandpa_pending_change(
+		let maybe_change = self.api.runtime_api().grandpa_pending_change(
 			&BlockId::hash(*block.header.parent_hash()),
 			&block.header.digest().clone(),
 		)?;
@@ -818,7 +818,7 @@ impl<B, E, Block: BlockT<Hash=H256>, RA> BlockImport<Block> for GrandpaBlockImpo
 			(old_set, authorities)
 		});
 
-		let result = self.inner.import_block(block, new_authorities);
+		let result = self.import.import_block(block, new_authorities);
 		if let Err(ref e) = result {
 			if let Some((old_set, mut authorities)) = just_in_case {
 				debug!(target: "afg", "Restoring old set after block import error: {:?}", e);
@@ -832,15 +832,15 @@ impl<B, E, Block: BlockT<Hash=H256>, RA> BlockImport<Block> for GrandpaBlockImpo
 
 /// Half of a link between a block-import worker and a the background voter.
 // This should remain non-clone.
-pub struct LinkHalf<B, E, Block: BlockT<Hash=H256>, RA> {
-	client: Arc<Client<B, E, Block, RA>>,
+pub struct LinkHalf<C, RA> {
+	client: C,
 	authority_set: SharedAuthoritySet<Block::Hash, NumberFor<Block>>,
 }
 
 /// Make block importer and link half necessary to tie the background voter
 /// to it.
-pub fn block_import<B, E, Block: BlockT<Hash=H256>, RA>(client: Arc<Client<B, E, Block, RA>>)
-	-> Result<(GrandpaBlockImport<B, E, Block, RA>, LinkHalf<B, E, Block, RA>), ClientError>
+pub fn block_import<C, Api>(client: Arc<Client<B, E, Block>>)
+	-> Result<(GrandpaBlockImport<C RA>, LinkHalf<B, E, Block, RA>), ClientError>
 	where
 		B: Backend<Block, Blake2Hasher> + 'static,
 		E: CallExecutor<Block, Blake2Hasher> + 'static + Clone + Send + Sync,
@@ -881,7 +881,7 @@ pub fn block_import<B, E, Block: BlockT<Hash=H256>, RA>(client: Arc<Client<B, E,
 /// block import worker that has already been instantiated with `block_import`.
 pub fn run_grandpa<B, E, Block: BlockT<Hash=H256>, N, RA>(
 	config: Config,
-	link: LinkHalf<B, E, Block, RA>,
+	link: LinkHalf<Client<B, E, Block, RA>>,
 	network: N,
 ) -> ::client::error::Result<impl Future<Item=(),Error=()>> where
 	Block::Hash: Ord,
diff --git a/substrate/core/test-client/src/block_builder_ext.rs b/substrate/core/test-client/src/block_builder_ext.rs
index 3c334b07a1..81e4bf756c 100644
--- a/substrate/core/test-client/src/block_builder_ext.rs
+++ b/substrate/core/test-client/src/block_builder_ext.rs
@@ -22,6 +22,7 @@ use keyring;
 use runtime;
 use runtime_primitives::traits::ProvideRuntimeApi;
 use client::block_builder::api::BlockBuilder;
+use client::runtime_api::Core as CoreAPI;
 
 /// Extension trait for test block builder.
 pub trait BlockBuilderExt {
@@ -31,7 +32,7 @@ pub trait BlockBuilderExt {
 
 impl<'a, A> BlockBuilderExt for client::block_builder::BlockBuilder<'a, runtime::Block, A> where
 	A: ProvideRuntimeApi + client::blockchain::HeaderBackend<runtime::Block> + 'a,
-	A::Api: BlockBuilder<runtime::Block>
+	A::Api: BlockBuilder<runtime::Block> + CoreAPI<runtime::Block>,
 {
 	fn push_transfer(&mut self, transfer: runtime::Transfer) -> Result<(), client::error::Error> {
 		self.push(sign_tx(transfer))