diff --git a/vm/types/src/on_chain_resource/block_metadata.rs b/vm/types/src/on_chain_resource/block_metadata.rs
index 4c6565ca95..3eb3afaea7 100644
--- a/vm/types/src/on_chain_resource/block_metadata.rs
+++ b/vm/types/src/on_chain_resource/block_metadata.rs
@@ -17,7 +17,7 @@ pub struct BlockMetadata {
     // number of the current block
     pub number: u64,
     // Hash of the parent block.
-    pub parent_hash: Vec<u8>,
+    pub parent_hash: HashValue,
     // Author of the current block.
     pub author: AccountAddress,
     // Uncle blocks number