diff --git a/packages/core/src/types/modifyReadResponse.ts b/packages/core/src/types/modifyReadResponse.ts
index ae552186..356c8b2b 100644
--- a/packages/core/src/types/modifyReadResponse.ts
+++ b/packages/core/src/types/modifyReadResponse.ts
@@ -3,17 +3,17 @@ import { DocMetadata } from './atoms'
 /**
  * Can be used to modify docs that come in from 'stream' or 'fetch' actions, before they are added to your store data. When returning `undefined` they will be discarded & won't be added to the store data.
  */
-export type OnAddedFn = (docData: Record<string, any> | undefined, docMetadata: DocMetadata) => Record<string, any> | void //prettier-ignore
+export type OnAddedFn = (docData: Record<string, any>, docMetadata: DocMetadata) => Record<string, any> | undefined //prettier-ignore
 
 /**
  * Is triggered only while a 'stream' is open, and can modify docs that were modified on another client, before they are updated to the store data. When returning `undefined` they will be discarded & the modifications won't be applied to the store data.
  */
-export type OnModifiedFn = (docData: Record<string, any> | undefined, docMetadata: DocMetadata) => Record<string, any> | void //prettier-ignore
+export type OnModifiedFn = (docData: Record<string, any>, docMetadata: DocMetadata) => Record<string, any> | undefined //prettier-ignore
 
 /**
  * Is triggered only while a 'stream' is open, every time a document is either 'deleted' on another client OR if a document doesn't adhere to the clauses of that 'stream' anymore. When returning `undefined` they will not be removed from the store data.
  */
-export type OnRemovedFn = (docData: Record<string, any> | string | undefined, docMetadata: DocMetadata) => Record<string, any> | string | void //prettier-ignore
+export type OnRemovedFn = (docData: Record<string, any> | string, docMetadata: DocMetadata) => Record<string, any> | string | undefined //prettier-ignore
 
 /**
  * These functions will be executed everytime BEFORE documents are added/modified/deleted in your local data store. The function defined will receive the payload with changes from the server. You can then modify and return this payload.