diff --git a/packages/core/src/genesis-provider.ts b/packages/core/src/genesis-provider.ts
index 73ff2529..d6fc034a 100644
--- a/packages/core/src/genesis-provider.ts
+++ b/packages/core/src/genesis-provider.ts
@@ -98,7 +98,7 @@ export class GenesisProvider implements ProviderInterface {
   getHeader = async () => {
     return {
       blockHash: this.blockHash,
-      number: 0,
+      number: '0x0' as HexString,
       stateRoot: await this.#stateRoot,
       digest: {
         logs: [],
diff --git a/packages/core/src/rpc/substrate/chain.ts b/packages/core/src/rpc/substrate/chain.ts
index 8a6cc9df..1aac14a6 100644
--- a/packages/core/src/rpc/substrate/chain.ts
+++ b/packages/core/src/rpc/substrate/chain.ts
@@ -56,7 +56,7 @@ export const chain_getBlock: Handler<
   }
   return {
     block: {
-      header: await block.header,
+      header: processHeader(await block.header),
       extrinsics: await block.extrinsics,
     },
     justifications: null,