diff --git a/lib/manager/preroller.ts b/lib/manager/preroller.ts
index ac65ca8..c2d95ac 100644
--- a/lib/manager/preroller.ts
+++ b/lib/manager/preroller.ts
@@ -6,12 +6,26 @@ import MimeType from "whatwg-mimetype";
 import { Download } from "./download";
 import { CHROME, webRequest } from "../browser";
 import { CDHeaderParser } from "../cdheaderparser";
-import { sanitizePath } from "../util";
+import { sanitizePath, parsePath } from "../util";
+import { MimeDB } from "../mime";
 
 const PREROLL_HEURISTICS = /dl|attach|download|name|file|get|retr|^n$|\.(php|asp|py|pl|action|htm|shtm)/i;
 const PREROLL_HOSTS = /4cdn|chan/;
 const PREROLL_TIMEOUT = 10000;
 const PREROLL_NOPE = new Set<string>();
+const PREROLL_SEARCHEXTS = Object.freeze(new Set<string>([
+  "php",
+  "asp",
+  "aspx",
+  "inc",
+  "py",
+  "pl",
+  "action",
+  "htm",
+  "html",
+  "shtml"
+]));
+const NAME_TESTER = /\.[a-z0-9]{1,5}$/i;
 const CDPARSER = new CDHeaderParser();
 
 export interface PrerollResults {
@@ -139,12 +153,37 @@ export class Preroller {
       rv.mime = type.essence;
     }
 
+    const {p_ext: ext} = this.download.renamer;
     const dispHeader = headers.get("content-disposition");
     if (dispHeader) {
       const file = CDPARSER.parse(dispHeader);
       // Sanitize
       rv.name = sanitizePath(file.replace(/[/\\]+/g, "-"));
     }
+    else if (!ext || PREROLL_SEARCHEXTS.has(ext.toLocaleLowerCase())) {
+      const {searchParams} = this.download.uURL;
+      let detected = "";
+      for (const [, value] of searchParams) {
+        if (!NAME_TESTER.test(value)) {
+          continue;
+        }
+        const p = parsePath(value);
+        if (!p.base || !p.ext) {
+          continue;
+        }
+        if (!MimeDB.hasExtension(p.ext)) {
+          continue;
+        }
+        const sanitized = sanitizePath(p.name);
+        if (sanitized.length <= detected.length) {
+          continue;
+        }
+        detected = sanitized;
+      }
+      if (detected) {
+        rv.name = detected;
+      }
+    }
 
     rv.finalURL = res.url;
 
diff --git a/lib/mime.ts b/lib/mime.ts
index 57e6c4e..a8e7cf4 100644
--- a/lib/mime.ts
+++ b/lib/mime.ts
@@ -28,6 +28,8 @@ export class MimeInfo {
 export const MimeDB = new class {
   private readonly mimeToExts: Map<string, MimeInfo>;
 
+  private readonly registeredExtensions: Set<string>;
+
   constructor() {
     const exts = new Map<string, string[]>();
     for (const [prim, more] of Object.entries(mime.e)) {
@@ -42,6 +44,10 @@ export const MimeDB = new class {
       Object.entries(mime.m),
       ([mime, prim]) => [mime, new MimeInfo(mime, exts.get(prim) || [prim])]
     ));
+    const all = Array.from(
+      this.mimeToExts.values(),
+      m => Array.from(m.extensions, e => e.toLowerCase()));
+    this.registeredExtensions = new Set(all.flat());
   }
 
   getPrimary(mime: string) {
@@ -52,4 +58,8 @@ export const MimeDB = new class {
   getMime(mime: string) {
     return this.mimeToExts.get(mime.trim().toLocaleLowerCase());
   }
+
+  hasExtension(ext: string) {
+    return this.registeredExtensions.has(ext.toLowerCase());
+  }
 }();