diff --git a/subxt/src/backend/unstable/follow_stream_unpin.rs b/subxt/src/backend/unstable/follow_stream_unpin.rs
index d4164a9d90..6a01f35e9b 100644
--- a/subxt/src/backend/unstable/follow_stream_unpin.rs
+++ b/subxt/src/backend/unstable/follow_stream_unpin.rs
@@ -115,15 +115,20 @@ impl<Hash: BlockHash> Stream for FollowStreamUnpin<Hash> {
                 }
                 FollowStreamMsg::Event(FollowEvent::Initialized(details)) => {
                     // The first finalized block gets the starting block_num.
-                    let rel_block_num = this.rel_block_num;
-                    // Pin this block, but note that it can be unpinned any time since it won't show up again (except
-                    // as a parent block, which we are ignoring at the moment).
+                    let mut rel_block_num = this.rel_block_num;
 
-                    let finalized_block_hashes = details
-                        .finalized_block_hashes
-                        .iter()
-                        .map(|h| this.pin_unpinnable_block_at(rel_block_num, *h))
-                        .collect();
+                    let mut finalized_block_hashes =
+                        Vec::with_capacity(details.finalized_block_hashes.len());
+
+                    for finalized_block in &details.finalized_block_hashes {
+                        // Pin this block, but note that it can be unpinned any time since it won't show up again (except
+                        // as a parent block, which we are ignoring at the moment).
+                        let block_ref =
+                            this.pin_unpinnable_block_at(rel_block_num, *finalized_block);
+
+                        finalized_block_hashes.push(block_ref);
+                        rel_block_num += 1;
+                    }
 
                     FollowStreamMsg::Event(FollowEvent::Initialized(Initialized {
                         finalized_block_hashes,
diff --git a/testing/integration-tests/src/full_client/client/unstable_rpcs.rs b/testing/integration-tests/src/full_client/client/unstable_rpcs.rs
index d32a5d9dea..66fcffdc9d 100644
--- a/testing/integration-tests/src/full_client/client/unstable_rpcs.rs
+++ b/testing/integration-tests/src/full_client/client/unstable_rpcs.rs
@@ -65,17 +65,14 @@ async fn chainhead_unstable_body() {
 
     let mut blocks = rpc.chainhead_unstable_follow(false).await.unwrap();
     let event = blocks.next().await.unwrap().unwrap();
-    let hashes = match event {
-        FollowEvent::Initialized(init) => init.finalized_block_hashes,
+    let hash = match event {
+        FollowEvent::Initialized(init) => init.finalized_block_hashes.last().unwrap().clone(),
         _ => panic!("Unexpected event"),
     };
     let sub_id = blocks.subscription_id().unwrap();
 
     // Fetch the block's body.
-    let response = rpc
-        .chainhead_unstable_body(sub_id, hashes[0])
-        .await
-        .unwrap();
+    let response = rpc.chainhead_unstable_body(sub_id, hash).await.unwrap();
     let operation_id = match response {
         MethodResponse::Started(started) => started.operation_id,
         MethodResponse::LimitReached => panic!("Expected started response"),
@@ -97,12 +94,11 @@ async fn chainhead_unstable_header() {
 
     let mut blocks = rpc.chainhead_unstable_follow(false).await.unwrap();
     let event = blocks.next().await.unwrap().unwrap();
-    let hashes = match event {
-        FollowEvent::Initialized(init) => init.finalized_block_hashes,
+    let hash = match event {
+        FollowEvent::Initialized(init) => init.finalized_block_hashes.last().unwrap().clone(),
         _ => panic!("Unexpected event"),
     };
     let sub_id = blocks.subscription_id().unwrap();
-    let hash = hashes[0];
 
     let new_header = legacy_rpc
         .chain_get_header(Some(hash))
@@ -126,12 +122,11 @@ async fn chainhead_unstable_storage() {
 
     let mut blocks = rpc.chainhead_unstable_follow(false).await.unwrap();
     let event = blocks.next().await.unwrap().unwrap();
-    let hashes = match event {
-        FollowEvent::Initialized(init) => init.finalized_block_hashes,
+    let hash = match event {
+        FollowEvent::Initialized(init) => init.finalized_block_hashes.last().unwrap().clone(),
         _ => panic!("Unexpected event"),
     };
     let sub_id = blocks.subscription_id().unwrap();
-    let hash = hashes[0];
 
     let alice: AccountId32 = dev::alice().public_key().into();
     let addr = node_runtime::storage().system().account(alice);
@@ -172,12 +167,11 @@ async fn chainhead_unstable_call() {
 
     let mut blocks = rpc.chainhead_unstable_follow(true).await.unwrap();
     let event = blocks.next().await.unwrap().unwrap();
-    let hashes = match event {
-        FollowEvent::Initialized(init) => init.finalized_block_hashes,
+    let hash = match event {
+        FollowEvent::Initialized(init) => init.finalized_block_hashes.last().unwrap().clone(),
         _ => panic!("Unexpected event"),
     };
     let sub_id = blocks.subscription_id().unwrap();
-    let hash = hashes[0];
 
     let alice_id = dev::alice().public_key().to_account_id();
     // Runtime API call.
@@ -210,12 +204,11 @@ async fn chainhead_unstable_unpin() {
 
     let mut blocks = rpc.chainhead_unstable_follow(true).await.unwrap();
     let event = blocks.next().await.unwrap().unwrap();
-    let hashes = match event {
-        FollowEvent::Initialized(init) => init.finalized_block_hashes,
+    let hash = match event {
+        FollowEvent::Initialized(init) => init.finalized_block_hashes.last().unwrap().clone(),
         _ => panic!("Unexpected event"),
     };
     let sub_id = blocks.subscription_id().unwrap();
-    let hash = hashes[0];
 
     assert!(rpc.chainhead_unstable_unpin(sub_id, hash).await.is_ok());
     // The block was already unpinned.