diff --git a/packages/state-transition/src/util/sszBytes.ts b/packages/state-transition/src/util/sszBytes.ts
index 25b65626a0dd..b5141e1673e5 100644
--- a/packages/state-transition/src/util/sszBytes.ts
+++ b/packages/state-transition/src/util/sszBytes.ts
@@ -37,14 +37,14 @@ export const VALIDATOR_BYTES_SIZE = 121;
  */
 const SLOT_BYTES_POSITION_IN_STATE = 40;
 
-export function getForkFromStateBytes(config: ChainForkConfig, bytes: Buffer | Uint8Array): ForkSeq {
+export function getForkFromStateBytes(config: ChainForkConfig, bytes: Uint8Array): ForkSeq {
   const slot = bytesToInt(bytes.subarray(SLOT_BYTES_POSITION_IN_STATE, SLOT_BYTES_POSITION_IN_STATE + SLOT_BYTE_COUNT));
   return config.getForkSeq(slot);
 }
 
 export function getStateTypeFromBytes(
   config: ChainForkConfig,
-  bytes: Buffer | Uint8Array
+  bytes: Uint8Array
 ): allForks.AllForksSSZTypes["BeaconState"] {
   const slot = getStateSlotFromBytes(bytes);
   return config.getForkTypes(slot).BeaconState;