diff --git a/packages/client/src/hook/useGalleryDoc.ts b/packages/client/src/hook/useGalleryDoc.ts
index 2708d70..9b24177 100644
--- a/packages/client/src/hook/useGalleryDoc.ts
+++ b/packages/client/src/hook/useGalleryDoc.ts
@@ -1,7 +1,17 @@
-import useSWR from "swr";
+import useSWR, { useSWRConfig } from "swr";
 import type { Document } from "dbtype";
 import { fetcher } from "./fetcher";
 
 export function useGalleryDoc(id: string) {
     return useSWR<Document>(`/api/doc/${id}`, fetcher);
+}
+
+export function useRehashDoc() {
+    const { mutate } = useSWRConfig();
+    return async (id: string) => {
+        await fetch(`/api/doc/${id}/_rehash`, {
+            method: "POST",
+        });
+        mutate(`/api/doc/${id}`);
+    };
 }
\ No newline at end of file
diff --git a/packages/client/src/page/contentInfoPage.tsx b/packages/client/src/page/contentInfoPage.tsx
index 9a86480..5438dec 100644
--- a/packages/client/src/page/contentInfoPage.tsx
+++ b/packages/client/src/page/contentInfoPage.tsx
@@ -1,10 +1,11 @@
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
-import { useGalleryDoc } from "../hook/useGalleryDoc.ts";
+import { useGalleryDoc, useRehashDoc } from "../hook/useGalleryDoc.ts";
 import TagBadge from "@/components/gallery/TagBadge";
 import StyledLink from "@/components/gallery/StyledLink";
 import { Link } from "wouter";
 import { classifyTags } from "../lib/classifyTags.tsx";
 import { DescTagItem, DescItem } from "../components/gallery/DescItem.tsx";
+import { Button } from "@/components/ui/button.tsx";
 
 export interface ContentInfoPageProps {
     params: {
@@ -14,6 +15,7 @@ export interface ContentInfoPageProps {
 
 export function ContentInfoPage({ params }: ContentInfoPageProps) {
     const { data, error, isLoading } = useGalleryDoc(params.id);
+    const rehashDoc = useRehashDoc();
 
     if (isLoading) {
         return <div className="p-4">Loading...</div>
@@ -43,7 +45,13 @@ export function ContentInfoPage({ params }: ContentInfoPageProps) {
                         alt={data.title} />
                 </div>
             </Link>
-            <Card className="flex-1">
+            <Card className="flex-1 relative">
+                <div className="absolute top-0 right-0 p-2">
+                    <Button variant="ghost" onClick={async () => { 
+                        // Rehash
+                        await rehashDoc(params.id);
+                     }}>Rehash</Button>
+                </div>
                 <CardHeader>
                     <CardTitle>
                         <StyledLink to={contentLocation}>
diff --git a/packages/server/src/route/contents.ts b/packages/server/src/route/contents.ts
index 8c37077..811b6b8 100644
--- a/packages/server/src/route/contents.ts
+++ b/packages/server/src/route/contents.ts
@@ -15,6 +15,8 @@ import { AllContentRouter } from "./all.ts";
 import type { ContentLocation } from "./context.ts";
 import { sendError } from "./error_handler.ts";
 import { ParseQueryArgString, ParseQueryArray, ParseQueryBoolean, ParseQueryNumber } from "./util.ts";
+import { oshash } from "src/util/oshash.ts";
+
 
 const ContentIDHandler = (controller: DocumentAccessor) => async (ctx: Context, next: Next) => {
 	const num = Number.parseInt(ctx.params.num);
@@ -154,6 +156,34 @@ const ContentHandler = (controller: DocumentAccessor) => async (ctx: Context, ne
 	await next();
 };
 
+function RehashContentHandler(controller: DocumentAccessor) {
+	return async (ctx: Context, next: Next) => {
+		const num = Number.parseInt(ctx.params.num);
+		const c = await controller.findById(num);
+		if (c === undefined || c.deleted_at !== null) {
+			return sendError(404);
+		}
+		const filepath = join(c.basepath, c.filename);
+		let new_hash: string;
+		try {
+			new_hash = (await oshash(filepath)).toString();
+		}
+		catch (e) {
+			// if file is not found, return 404
+			if ( (e as NodeJS.ErrnoException).code === "ENOENT") {
+				return sendError(404, "file not found");
+			}
+			throw e;
+		}
+		const r = await controller.update({
+			id: num,
+			content_hash: new_hash,
+		});
+		ctx.body = JSON.stringify(r);
+		ctx.type = "json";
+	};
+}
+
 export const getContentRouter = (controller: DocumentAccessor) => {
 	const ret = new Router();
 	ret.get("/search", PerCheck(Per.QueryContent), ContentQueryHandler(controller));
@@ -167,6 +197,7 @@ export const getContentRouter = (controller: DocumentAccessor) => {
 	ret.del("/:num(\\d+)", AdminOnly, DeleteContentHandler(controller));
 	ret.all("/:num(\\d+)/(.*)", PerCheck(Per.QueryContent), ContentHandler(controller));
 	ret.use("/:num(\\d+)", PerCheck(Per.QueryContent), new AllContentRouter().routes());
+	ret.post("/:num(\\d+)/_rehash", AdminOnly, RehashContentHandler(controller));
 	return ret;
 };