diff --git a/programs/validator-history/Cargo.toml b/programs/validator-history/Cargo.toml
index b813a273..bd681120 100644
--- a/programs/validator-history/Cargo.toml
+++ b/programs/validator-history/Cargo.toml
@@ -20,6 +20,7 @@ no-log-ix-name = []
 cpi = ["no-entrypoint"]
 default = ["custom-heap"]
 custom-heap = []
+testnet = []
 
 [dependencies]
 anchor-lang = "0.28.0"
diff --git a/programs/validator-history/src/instructions/copy_cluster_info.rs b/programs/validator-history/src/instructions/copy_cluster_info.rs
index a6d7310d..397fcde7 100644
--- a/programs/validator-history/src/instructions/copy_cluster_info.rs
+++ b/programs/validator-history/src/instructions/copy_cluster_info.rs
@@ -60,8 +60,7 @@ pub fn handle_copy_cluster_info(ctx: Context<CopyClusterInfo>) -> Result<()> {
     };
 
     let start_slot = epoch_schedule.get_first_slot_in_epoch(epoch.into());
-    let end_slot = epoch_schedule.get_last_slot_in_epoch(epoch.into());
-    let (num_blocks, _) = confirmed_blocks_in_epoch(start_slot, end_slot, *slot_history)?;
+    let (num_blocks, _) = confirmed_blocks_in_epoch(start_slot, clock.slot, *slot_history)?;
     cluster_history_account.set_blocks(epoch, num_blocks)?;
     cluster_history_account.set_epoch_start_timestamp(epoch, epoch_start_timestamp)?;
 
@@ -95,11 +94,13 @@ pub fn confirmed_blocks_in_epoch(
                     .ok_or(ValidatorHistoryError::ArithmeticError)?,
             )
             .ok_or(ValidatorHistoryError::ArithmeticError)?
+            .min(end_slot)
     };
 
     let last_full_block_slot = end_slot
         .checked_sub(end_slot % BITVEC_BLOCK_SIZE)
-        .ok_or(ValidatorHistoryError::ArithmeticError)?;
+        .ok_or(ValidatorHistoryError::ArithmeticError)?
+        .max(first_full_block_slot);
 
     // First and last slots, in partial blocks
     for i in (start_slot..first_full_block_slot).chain(last_full_block_slot..=end_slot) {
diff --git a/tests/tests/test_cluster_history.rs b/tests/tests/test_cluster_history.rs
index b900112f..97242c97 100644
--- a/tests/tests/test_cluster_history.rs
+++ b/tests/tests/test_cluster_history.rs
@@ -74,13 +74,15 @@ async fn test_copy_cluster_info() {
         .await
         .expect("clock");
 
-    assert!(clock.epoch == 1);
     assert!(account.history.idx == 1);
     assert!(account.history.arr[0].epoch == 0);
     assert!(account.history.arr[0].total_blocks == 3);
+    assert!(clock.epoch == 1);
+    assert!(clock.slot == 32);
+    assert!(clock.slot == latest_slot);
+    assert!(account.cluster_history_last_update_slot == latest_slot);
     assert!(account.history.arr[1].epoch == 1);
-    assert!(account.history.arr[1].total_blocks == 2);
-    assert_eq!(account.cluster_history_last_update_slot, latest_slot)
+    assert!(account.history.arr[1].total_blocks == 1);
 }
 
 #[tokio::test]
@@ -170,7 +172,7 @@ async fn test_cluster_history_compute_limit() {
     assert!(account.history.arr[0].epoch as u64 == clock.epoch - 1);
     assert!(account.history.arr[0].total_blocks == 216_000);
     assert!(account.history.arr[1].epoch as u64 == clock.epoch);
-    assert!(account.history.arr[1].total_blocks == 216_000);
+    assert!(account.history.arr[1].total_blocks == 1);
 }
 
 // Non-fixture test to ensure that the SlotHistory partial slot logic works
@@ -183,6 +185,18 @@ fn test_confirmed_blocks_in_epoch_partial_blocks() {
     // First partial block: 50 -> 64
     // Full block: 64 -> 127
     // Last partial block: 128 -> 149
-    let (num_blocks, _) = confirmed_blocks_in_epoch(50, 149, slot_history).unwrap();
+    let (num_blocks, _) = confirmed_blocks_in_epoch(50, 149, slot_history.clone()).unwrap();
     assert_eq!(num_blocks, 100);
+
+    let (num_blocks, _) = confirmed_blocks_in_epoch(50, 99, slot_history.clone()).unwrap();
+    assert_eq!(num_blocks, 50);
+
+    let (num_blocks, _) = confirmed_blocks_in_epoch(64, 127, slot_history.clone()).unwrap();
+    assert_eq!(num_blocks, 64);
+
+    let (num_blocks, _) = confirmed_blocks_in_epoch(64, 64, slot_history.clone()).unwrap();
+    assert_eq!(num_blocks, 1);
+
+    let (num_blocks, _) = confirmed_blocks_in_epoch(100, 149, slot_history.clone()).unwrap();
+    assert_eq!(num_blocks, 50);
 }