diff --git a/tasks/download.ts b/tasks/download.ts
index ea2b5f2..baee540 100644
--- a/tasks/download.ts
+++ b/tasks/download.ts
@@ -16,11 +16,12 @@ import {
     asyncFilter,
     promiseState,
     PromiseStatus,
+    replaceExtname,
     sleep,
     sure_dir,
     TimeoutError,
 } from "../utils.ts";
-import { join, resolve } from "@std/path";
+import { basename, extname, join, resolve } from "@std/path";
 import { exists } from "@std/fs/exists";
 import { ProgressReadable } from "../utils/progress_readable.ts";
 
@@ -162,6 +163,11 @@ class DownloadManager {
         }
         this.#sendEvent();
     }
+    set_details_name(index: number, name: string) {
+        const d = this.#progress.details.find((v) => v.index === index);
+        if (d) d.name = name;
+        this.#sendEvent();
+    }
     set_details_started(index: number) {
         const d = this.#progress.details.find((v) => v.index === index);
         if (d) {
@@ -369,6 +375,20 @@ export async function download_task(
                         pr.addEventListener("progress", (e) => {
                             m.set_details_downloaded(i.index, e.detail);
                         });
+                        if (!download_original) {
+                            const ext = extname(path);
+                            const u = new URL(re.url);
+                            const uext = extname(u.pathname);
+                            if (ext != uext) {
+                                path = replaceExtname(path, uext);
+                                if (f) {
+                                    f.path = path;
+                                } else {
+                                    throw Error("Failed to get file.");
+                                }
+                                m.set_details_name(i.index, basename(path));
+                            }
+                        }
                         try {
                             const f = await Deno.open(path, {
                                 create: true,
diff --git a/utils.ts b/utils.ts
index c53e18e..2481e9b 100644
--- a/utils.ts
+++ b/utils.ts
@@ -335,21 +335,27 @@ export function compareNum(num1: number | bigint, num2: number | bigint) {
 
 const HASH_PATTERN = /^\/h\/([0-9a-f]+)/;
 const FHASH_PATTERN = /([0-9a-f]{40})-(\d+)-(\d+)-(\d+)-([^\/]+)/g;
+const EXT_MAP: Record<string, string> = {
+    ".jpg": "jpg",
+    ".png": "png",
+    ".webp": "wbp",
+};
 
 export function getHashFromUrl(url: string | URL) {
     const u = typeof url === "string" ? new URL(url) : url;
     const m = u.pathname.match(HASH_PATTERN);
     if (m) return m[1];
     if (u.pathname.startsWith("/om/")) {
+        const ext = EXT_MAP[extname(u.pathname)];
         const ma = Array.from(u.pathname.matchAll(FHASH_PATTERN));
         const comps = u.pathname.split("/");
         if (ma.length && comps.length > 3) {
-            const width = comps[comps.length - 3];
-            if (width == "0") {
+            const width = parseInt(comps[comps.length - 3]);
+            if (width === 0) {
                 return ma[0][1];
             }
             for (const f of ma) {
-                if (f[3] == width) {
+                if (parseInt(f[3]) <= width && f[5] == ext) {
                     return f[1];
                 }
             }
@@ -357,3 +363,17 @@ export function getHashFromUrl(url: string | URL) {
     }
     throw Error(`URL ${url} not contains hash info.`);
 }
+
+/**
+ * Replaces the file extension of a given path with a new extension.
+ *
+ * @param path - The original file path from which the extension will be replaced.
+ * @param ext - The new extension to be used. If it does not start with a dot, one will be added.
+ * @returns The modified file path with the new extension.
+ */
+export function replaceExtname(path: string, ext: string) {
+    if (ext && !ext.startsWith(".")) {
+        ext = "." + ext;
+    }
+    return path.slice(0, path.length - extname(path).length) + ext;
+}
diff --git a/utils_test.ts b/utils_test.ts
index 075e3f9..8cd1a74 100644
--- a/utils_test.ts
+++ b/utils_test.ts
@@ -14,6 +14,7 @@ import {
     parseBigInt,
     promiseState,
     PromiseStatus,
+    replaceExtname,
     sleep,
     sure_dir,
     toJSON,
@@ -227,4 +228,18 @@ Deno.test("getHashFromUrl_test", () => {
         ),
         "4038f0c078b59736aeaa5b1ce38a44b701238363",
     );
+    assertEquals(
+        getHashFromUrl(
+            "https://zurswtyclg.hath.network/om/160618900/ff92f8c044e42cdcadcc0bb35d4bc957d1b00c93-3221277-2419-3482-png/109caa716cd3ac3b8ccf4e1e6c1290cc40e72984-100408-2419-3482-wbp/2560/eoqq7x49z16j8q1jeha/12.webp",
+        ),
+        "109caa716cd3ac3b8ccf4e1e6c1290cc40e72984",
+    );
+});
+
+Deno.test("replaceExtname_test", () => {
+    assertEquals(replaceExtname("test.ts", "js"), "test.js");
+    assertEquals(replaceExtname("test", "js"), "test.js");
+    assertEquals(replaceExtname("test.ts", ""), "test");
+    assertEquals(replaceExtname("test", ""), "test");
+    assertEquals(replaceExtname("test", "."), "test.");
 });