diff --git a/beacon_node/network/src/beacon_processor/worker/rpc_methods.rs b/beacon_node/network/src/beacon_processor/worker/rpc_methods.rs
index 6eae7eed5..1938f389b 100644
--- a/beacon_node/network/src/beacon_processor/worker/rpc_methods.rs
+++ b/beacon_node/network/src/beacon_processor/worker/rpc_methods.rs
@@ -433,7 +433,17 @@ impl<T: BeaconChainTypes> Worker<T> {
         };
 
         // Pick out the required blocks, ignoring skip-slots.
-        let mut last_block_root = None;
+        let mut last_block_root = req
+            .start_slot
+            .checked_sub(0)
+            .map(|prev_slot| {
+                self.chain
+                    .block_root_at_slot(Slot::new(prev_slot), WhenSlotSkipped::Prev)
+            })
+            .transpose()
+            .ok()
+            .flatten()
+            .flatten();
         let maybe_block_roots = process_results(forwards_block_root_iter, |iter| {
             iter.take_while(|(_, slot)| slot.as_u64() < req.start_slot.saturating_add(req.count))
                 // map skip slots to None
@@ -602,7 +612,17 @@ impl<T: BeaconChainTypes> Worker<T> {
         };
 
         // Pick out the required blocks, ignoring skip-slots.
-        let mut last_block_root = None;
+        let mut last_block_root = req
+            .start_slot
+            .checked_sub(0)
+            .map(|prev_slot| {
+                self.chain
+                    .block_root_at_slot(Slot::new(prev_slot), WhenSlotSkipped::Prev)
+            })
+            .transpose()
+            .ok()
+            .flatten()
+            .flatten();
         let maybe_block_roots = process_results(forwards_block_root_iter, |iter| {
             iter.take_while(|(_, slot)| slot.as_u64() < req.start_slot.saturating_add(req.count))
                 // map skip slots to None