diff --git a/substrate/client/consensus/common/src/import_queue.rs b/substrate/client/consensus/common/src/import_queue.rs
index 35fc8ad4a402..1baa67398a49 100644
--- a/substrate/client/consensus/common/src/import_queue.rs
+++ b/substrate/client/consensus/common/src/import_queue.rs
@@ -225,7 +225,7 @@ pub async fn import_single_block<B: BlockT, V: Verifier<B>>(
 	import_handle: &mut impl BlockImport<B, Error = ConsensusError>,
 	block_origin: BlockOrigin,
 	block: IncomingBlock<B>,
-	verifier: &mut V,
+	verifier: &V,
 ) -> BlockImportResult<B> {
 	match verify_single_block_metered(import_handle, block_origin, block, verifier, None).await? {
 		SingleBlockVerificationOutcome::Imported(import_status) => Ok(import_status),
@@ -295,7 +295,7 @@ pub(crate) async fn verify_single_block_metered<B: BlockT, V: Verifier<B>>(
 	import_handle: &impl BlockImport<B, Error = ConsensusError>,
 	block_origin: BlockOrigin,
 	block: IncomingBlock<B>,
-	verifier: &mut V,
+	verifier: &V,
 	metrics: Option<&Metrics>,
 ) -> Result<SingleBlockVerificationOutcome<B>, BlockImportError> {
 	let peer = block.origin;
diff --git a/substrate/client/consensus/common/src/import_queue/basic_queue.rs b/substrate/client/consensus/common/src/import_queue/basic_queue.rs
index 05f2b2527961..6a307acb2517 100644
--- a/substrate/client/consensus/common/src/import_queue/basic_queue.rs
+++ b/substrate/client/consensus/common/src/import_queue/basic_queue.rs
@@ -222,7 +222,7 @@ mod worker_messages {
 /// Returns when `block_import` ended.
 async fn block_import_process<B: BlockT>(
 	mut block_import: BoxBlockImport<B>,
-	mut verifier: impl Verifier<B>,
+	verifier: impl Verifier<B>,
 	mut result_sender: BufferedLinkSender<B>,
 	mut block_import_receiver: TracingUnboundedReceiver<worker_messages::ImportBlocks<B>>,
 	metrics: Option<Metrics>,
@@ -241,8 +241,7 @@ async fn block_import_process<B: BlockT>(
 		};
 
 		let res =
-			import_many_blocks(&mut block_import, origin, blocks, &mut verifier, metrics.clone())
-				.await;
+			import_many_blocks(&mut block_import, origin, blocks, &verifier, metrics.clone()).await;
 
 		result_sender.blocks_processed(res.imported, res.block_count, res.results);
 	}
@@ -388,7 +387,7 @@ async fn import_many_blocks<B: BlockT, V: Verifier<B>>(
 	import_handle: &mut BoxBlockImport<B>,
 	blocks_origin: BlockOrigin,
 	blocks: Vec<IncomingBlock<B>>,
-	verifier: &mut V,
+	verifier: &V,
 	metrics: Option<Metrics>,
 ) -> ImportManyBlocksResult<B> {
 	let count = blocks.len();
diff --git a/substrate/client/network/test/src/block_import.rs b/substrate/client/network/test/src/block_import.rs
index 690a579e0272..dad5a27e9535 100644
--- a/substrate/client/network/test/src/block_import.rs
+++ b/substrate/client/network/test/src/block_import.rs
@@ -78,7 +78,7 @@ fn import_single_good_block_works() {
 		&mut substrate_test_runtime_client::new(),
 		BlockOrigin::File,
 		block,
-		&mut PassThroughVerifier::new(true),
+		&PassThroughVerifier::new(true),
 	)) {
 		Ok(BlockImportStatus::ImportedUnknown(ref num, ref aux, ref org))
 			if *num == number && *aux == expected_aux && *org == Some(peer_id.into()) => {},
@@ -93,7 +93,7 @@ fn import_single_good_known_block_is_ignored() {
 		&mut client,
 		BlockOrigin::File,
 		block,
-		&mut PassThroughVerifier::new(true),
+		&PassThroughVerifier::new(true),
 	)) {
 		Ok(BlockImportStatus::ImportedKnown(ref n, _)) if *n == number => {},
 		_ => panic!(),
@@ -108,7 +108,7 @@ fn import_single_good_block_without_header_fails() {
 		&mut substrate_test_runtime_client::new(),
 		BlockOrigin::File,
 		block,
-		&mut PassThroughVerifier::new(true),
+		&PassThroughVerifier::new(true),
 	)) {
 		Err(BlockImportError::IncompleteHeader(ref org)) if *org == Some(peer_id.into()) => {},
 		_ => panic!(),