diff --git a/packages/beacon-node/src/chain/chain.ts b/packages/beacon-node/src/chain/chain.ts
index fccce46da326..31068d20de27 100644
--- a/packages/beacon-node/src/chain/chain.ts
+++ b/packages/beacon-node/src/chain/chain.ts
@@ -791,7 +791,7 @@ export class BeaconChain implements IBeaconChain {
         this.producedBlobSidecarsCache,
         this.opts.maxCachedBlobSidecars ?? DEFAULT_MAX_CACHED_BLOB_SIDECARS
       );
-      this.metrics?.blockProductionCaches.producedBlobSidecarsCache.set(this.producedBlockRoot.size);
+      this.metrics?.blockProductionCaches.producedBlobSidecarsCache.set(this.producedBlobSidecarsCache.size);
     }
 
     const metrics = this.metrics;