diff --git a/packages/protocol/packages/payload/packages/model/src/PayloadValidationFunction.ts b/packages/protocol/packages/payload/packages/model/src/PayloadValidationFunction.ts
index fbcb48822b..f2a2932261 100644
--- a/packages/protocol/packages/payload/packages/model/src/PayloadValidationFunction.ts
+++ b/packages/protocol/packages/payload/packages/model/src/PayloadValidationFunction.ts
@@ -1,6 +1,16 @@
 import type { Payload } from './Payload.ts'
 
+/**
+ * A function that validates the supplied payload synchronously
+ */
+export type SyncPayloadValidationFunction<T extends Payload = Payload> = (payload: T) => boolean
+
+/**
+ * A function that validates the supplied payload asynchronously
+ */
+export type AsyncPayloadValidationFunction<T extends Payload = Payload> = (payload: T) => Promise<boolean>
+
 /**
  * A function that validates the supplied payload
  */
-export type PayloadValidationFunction<T extends Payload = Payload> = (payload: T) => boolean | Promise<boolean>
+export type PayloadValidationFunction<T extends Payload = Payload> = SyncPayloadValidationFunction<T> | AsyncPayloadValidationFunction<T>