diff --git a/db.ts b/db.ts
index 7eefc29..9e05e51 100644
--- a/db.ts
+++ b/db.ts
@@ -95,7 +95,6 @@ const TASK_TABLE = `CREATE TABLE task (
     type INT,
     gid INT,
     token TEXT,
-    pn INT,
     pid INT,
     details TEXT
 );`;
@@ -156,7 +155,7 @@ export class EhDb {
     #lock_file: string | undefined;
     #dblock_file: string | undefined;
     #_tags: Map<string, number> | undefined;
-    readonly version = new SemVer("1.0.0-4");
+    readonly version = new SemVer("1.0.0-5");
     constructor(base_path: string) {
         const db_path = join(base_path, "data.db");
         sure_dir_sync(base_path);
@@ -223,6 +222,9 @@ export class EhDb {
                 this.db.execute("DROP TABLE pmeta_origin;");
                 need_optimize = true;
             }
+            if (v.compare("1.0.0-5") === -1) {
+                this.db.execute("ALTER TABLE task DROP pn;");
+            }
             this.#write_version();
             if (need_optimize) this.optimize();
         }
@@ -361,35 +363,32 @@ export class EhDb {
     add_task(task: Task) {
         return this.transaction(() => {
             this.db.query(
-                "INSERT INTO task (type, gid, token, pn, pid, details) VALUES (?, ?, ?, ?, ?, ?);",
+                "INSERT INTO task (type, gid, token, pid, details) VALUES (?, ?, ?, ?, ?);",
                 [
                     task.type,
                     task.gid,
                     task.token,
-                    task.pn,
                     task.pid,
                     task.details,
                 ],
             );
             if (task.details === null) {
                 return this.db.queryEntries<Task>(
-                    "SELECT * FROM task WHERE type = ? AND gid = ? AND token = ? AND pn = ? AND pid = ?;",
+                    "SELECT * FROM task WHERE type = ? AND gid = ? AND token = ? AND pid = ?;",
                     [
                         task.type,
                         task.gid,
                         task.token,
-                        task.pn,
                         task.pid,
                     ],
                 )[0];
             }
             return this.db.queryEntries<Task>(
-                "SELECT * FROM task WHERE type = ? AND gid = ? AND token = ? AND pn = ? AND pid = ? AND details = ?;",
+                "SELECT * FROM task WHERE type = ? AND gid = ? AND token = ? AND pid = ? AND details = ?;",
                 [
                     task.type,
                     task.gid,
                     task.token,
-                    task.pn,
                     task.pid,
                     task.details,
                 ],
diff --git a/db_test.ts b/db_test.ts
index 76db8f5..70cc2af 100644
--- a/db_test.ts
+++ b/db_test.ts
@@ -13,7 +13,6 @@ Deno.test("DbTest", async () => {
             gid: 1,
             token: "dd",
             pid: 1,
-            pn: 1,
             type: TaskType.Download,
             id: 0,
             details: null,
@@ -24,7 +23,6 @@ Deno.test("DbTest", async () => {
             gid: 1,
             token: "dd",
             pid: 1,
-            pn: 1,
             type: TaskType.ExportZip,
             id: 0,
             details: "test",
diff --git a/task.ts b/task.ts
index 1e2ab32..89eec5b 100644
--- a/task.ts
+++ b/task.ts
@@ -8,7 +8,6 @@ export type Task = {
     type: TaskType;
     gid: number;
     token: string;
-    pn: number;
     pid: number;
     details: string | null;
 };
diff --git a/task_manager.ts b/task_manager.ts
index 04e8b24..d76d665 100644
--- a/task_manager.ts
+++ b/task_manager.ts
@@ -43,7 +43,7 @@ export class TaskManager extends EventTarget {
     }
     async #add_task(task: Task) {
         const r = await this.db.add_task(task);
-        this.dispatchEvent(new CustomEvent("new_task", { detail: r }));
+        this.dispatchEvent("new_task", r);
         return r;
     }
     #check_closed() {
@@ -78,7 +78,6 @@ export class TaskManager extends EventTarget {
             token,
             id: 0,
             pid: Deno.pid,
-            pn: 1,
             type: TaskType.Download,
             details: null,
         };
@@ -91,7 +90,6 @@ export class TaskManager extends EventTarget {
             token: "",
             id: 0,
             pid: Deno.pid,
-            pn: 0,
             type: TaskType.ExportZip,
             details: JSON.stringify(cfg),
         };
@@ -125,9 +123,7 @@ export class TaskManager extends EventTarget {
             if (status.status == PromiseStatus.Fulfilled && status.value) {
                 removed_task.push(id);
                 await this.db.delete_task(status.value);
-                this.dispatchEvent(
-                    new CustomEvent("task_finished", { detail: status.value }),
-                );
+                this.dispatchEvent("task_finished", status.value);
             } else if (status.status == PromiseStatus.Rejected) {
                 if (status.reason && !this.aborted) console.log(status.reason);
                 removed_task.push(id);
@@ -145,6 +141,10 @@ export class TaskManager extends EventTarget {
         this.#closed = true;
         this.db.close();
     }
+    // @ts-ignore Checked type
+    dispatchEvent<T extends keyof EventMap>(type: T, detail: EventMap[T]) {
+        return super.dispatchEvent(new CustomEvent(type, { detail }));
+    }
     force_abort(reason?: unknown) {
         this.#force_abort.abort(reason);
     }
@@ -223,7 +223,7 @@ export class TaskManager extends EventTarget {
                 ),
             );
         }
-        this.dispatchEvent(new CustomEvent("task_started", { detail: task }));
+        this.dispatchEvent("task_started", task);
     }
     async waiting_unfinished_task() {
         while (1) {