diff --git a/substrate/client/api/src/notifications.rs b/substrate/client/api/src/notifications.rs
index 13bf06396d..72a9f357fc 100644
--- a/substrate/client/api/src/notifications.rs
+++ b/substrate/client/api/src/notifications.rs
@@ -323,7 +323,7 @@ mod tests {
 			let child_filters = Some([
 				(StorageKey(vec![4]), None),
 				(StorageKey(vec![5]), None),
-			].into_iter().cloned().collect());
+			].iter().cloned().collect());
 			StorageChangeSet {
 				changes: Arc::new(changes.0),
 				child_changes: Arc::new(changes.1),
diff --git a/substrate/client/cli/src/node_key.rs b/substrate/client/cli/src/node_key.rs
index 4df3b8e9d5..88102acc63 100644
--- a/substrate/client/cli/src/node_key.rs
+++ b/substrate/client/cli/src/node_key.rs
@@ -113,7 +113,7 @@ mod tests {
 	#[test]
 	fn test_node_key_config_input() {
 		fn secret_input(net_config_dir: Option<String>) -> error::Result<()> {
-			NodeKeyType::variants().into_iter().try_for_each(|t| {
+			NodeKeyType::variants().iter().try_for_each(|t| {
 				let node_key_type = NodeKeyType::from_str(t).unwrap();
 				let sk = match node_key_type {
 					NodeKeyType::Ed25519 => ed25519::SecretKey::generate().as_ref().to_vec()
@@ -139,7 +139,7 @@ mod tests {
 	#[test]
 	fn test_node_key_config_file() {
 		fn secret_file(net_config_dir: Option<String>) -> error::Result<()> {
-			NodeKeyType::variants().into_iter().try_for_each(|t| {
+			NodeKeyType::variants().iter().try_for_each(|t| {
 				let node_key_type = NodeKeyType::from_str(t).unwrap();
 				let tmp = tempfile::Builder::new().prefix("alice").tempdir()?;
 				let file = tmp.path().join(format!("{}_mysecret", t)).to_path_buf();
@@ -166,7 +166,7 @@ mod tests {
 		where
 			F: Fn(NodeKeyParams) -> error::Result<()>
 		{
-			NodeKeyType::variants().into_iter().try_for_each(|t| {
+			NodeKeyType::variants().iter().try_for_each(|t| {
 				let node_key_type = NodeKeyType::from_str(t).unwrap();
 				f(NodeKeyParams {
 					node_key_type,
diff --git a/substrate/frame/staking/reward-curve/src/lib.rs b/substrate/frame/staking/reward-curve/src/lib.rs
index 89a1980d19..3c31cecc21 100644
--- a/substrate/frame/staking/reward-curve/src/lib.rs
+++ b/substrate/frame/staking/reward-curve/src/lib.rs
@@ -386,7 +386,7 @@ fn generate_test_module(input: &INposInput) -> TokenStream2 {
 
 			#[test]
 			fn reward_curve_precision() {
-				for &base in [MILLION, u32::max_value()].into_iter() {
+				for &base in [MILLION, u32::max_value()].iter() {
 					let number_of_check = 100_000.min(base);
 					for check_index in 0..=number_of_check {
 						let i = (check_index as u64 * base as u64 / number_of_check as u64) as u32;