diff --git a/examples/nextjs/src/app/[slug]/page.tsx b/examples/nextjs/src/app/[slug]/page.tsx
index 98d6b53..d94d2e4 100644
--- a/examples/nextjs/src/app/[slug]/page.tsx
+++ b/examples/nextjs/src/app/[slug]/page.tsx
@@ -23,16 +23,16 @@ export default async function SlugPage({ params }: { params: { slug: string } })
       blocks={blocks}
       options={{
         // Example customization: Render dates as German dates
-        formatDateFn: (date: Date) => {
-          return date.toLocaleDateString("de", {
+        formatDateFn: (dateString: string) => {
+          return new Date(dateString).toLocaleDateString("de", {
             month: "long",
             day: "numeric",
             year: "numeric",
           })
         },
         // Example resolving links to other Notion pages
-        resolveLinkFn: (nId) => {
-          const page = pages.find((p) => p.blockId === nId)
+        resolveLinkFn: (pageId) => {
+          const page = pages.find((p) => p.blockId === pageId)
           if (page === undefined) {
             return null
           }
diff --git a/packages/render/src/block.tsx b/packages/render/src/block.tsx
index cf67c12..595769f 100644
--- a/packages/render/src/block.tsx
+++ b/packages/render/src/block.tsx
@@ -12,8 +12,8 @@ import { PageTitle } from "./components/page-title"
 import { Code } from "./components/html/code"
 import { Img } from "./components/html/img"
 
-const defaultFormatDateFn = (date: Date) => date.toString()
-const defaultResolveLinkFn = (nId: string) => null
+const defaultFormatDateFn = (dateString: string) => new Date(dateString).toString()
+const defaultResolveLinkFn = (pageId: string) => null
 
 export const Render = ({
   blocks,
@@ -21,8 +21,8 @@ export const Render = ({
 }: {
   blocks: Array<BlockObjectResponseWithChildren>
   options?: {
-    formatDateFn?: (date: Date) => string
-    resolveLinkFn?: (nId: string) => { href: string; icon: IconResponse | null } | null
+    formatDateFn?: (dateString: string) => string
+    resolveLinkFn?: (pageId: string) => { href: string; icon: IconResponse | null } | null
     htmlComponents?: {
       a?: (props: React.ComponentPropsWithoutRef<"a">) => JSX.Element
       code?: (props: React.ComponentPropsWithoutRef<"code">) => JSX.Element
diff --git a/packages/render/src/components/text.tsx b/packages/render/src/components/text.tsx
index a0917b9..735d744 100644
--- a/packages/render/src/components/text.tsx
+++ b/packages/render/src/components/text.tsx
@@ -4,7 +4,7 @@ import type {
   TextRichTextItemResponse,
 } from "@notionhq/client/build/src/api-endpoints"
 
-import { cn, notionColor, notionLinkToUuid, notionUrl } from "../util"
+import { cn, notionColor, notionLinkToUuid } from "../util"
 import { RenderOptions } from "../types"
 import { PageTitle } from "./page-title"
 
@@ -109,15 +109,15 @@ const FormattedText = ({
   )
 }
 
-const mentionText = (value: MentionRichTextItemResponse, formatDateFn: (date: Date) => string) => {
+const mentionText = (value: MentionRichTextItemResponse, formatDateFn: (dateString: string) => string) => {
   switch (value.mention.type) {
     case "database":
       return null
     case "date":
       try {
-        let dateText = formatDateFn(new Date(value.mention.date.start))
+        let dateText = formatDateFn(value.mention.date.start)
         if (value.mention.date.end) {
-          dateText += ` → ${formatDateFn(new Date(value.mention.date.end))}`
+          dateText += ` → ${formatDateFn(value.mention.date.end)}`
         }
         // Ignored: value.mention.date.time_zone
         return dateText
diff --git a/packages/render/src/types.ts b/packages/render/src/types.ts
index f681b75..7676b2a 100644
--- a/packages/render/src/types.ts
+++ b/packages/render/src/types.ts
@@ -10,8 +10,8 @@ export type BlockObjectResponseWithChildren = BlockObjectResponse & {
 export type IconResponse = PageObjectResponse["icon"]
 
 export type RenderOptions = {
-  formatDateFn: (date: Date) => string
-  resolveLinkFn: (nId: string) => { href: string; icon: IconResponse | null } | null
+  formatDateFn: (dateString: string) => string
+  resolveLinkFn: (pageId: string) => { href: string; icon: IconResponse | null } | null
   htmlComponents: {
     a: (props: React.ComponentPropsWithoutRef<"a">) => JSX.Element
     code: (props: React.ComponentPropsWithoutRef<"code">) => JSX.Element