diff --git a/packages/hydrooj/src/handler/problem.ts b/packages/hydrooj/src/handler/problem.ts
index ea342332e..620694ce5 100644
--- a/packages/hydrooj/src/handler/problem.ts
+++ b/packages/hydrooj/src/handler/problem.ts
@@ -2,7 +2,7 @@ import AdmZip from 'adm-zip';
 import { readFile, statSync } from 'fs-extra';
 import { isBinaryFile } from 'isbinaryfile';
 import {
-    escapeRegExp, flattenDeep, intersection, isSafeInteger, pick,
+    escapeRegExp, flattenDeep, intersection, isSafeInteger, pick, uniqBy,
 } from 'lodash';
 import { FilterQuery, ObjectID } from 'mongodb';
 import { nanoid } from 'nanoid';
@@ -997,13 +997,15 @@ export class ProblemPrefixListHandler extends Handler {
             const pdoc = await problem.get(domainId, +prefix, ['domainId', 'docId', 'pid', 'title']);
             if (pdoc) pdocs.unshift(pdoc);
         }
+        const pdoc = await problem.get(domainId, prefix, ['domainId', 'docId', 'pid', 'title']);
+        if (pdoc) pdocs.unshift(pdoc);
         if (pdocs.length < 20) {
             const search = global.Hydro.lib.problemSearch || defaultSearch;
             const result = await search(domainId, prefix, { limit: 20 - pdocs.length });
             const docs = await problem.getMulti(domainId, { docId: { $in: result.hits.map((i) => +i.split('/')[1]) } }).toArray();
             pdocs.push(...docs);
         }
-        this.response.body = pdocs;
+        this.response.body = uniqBy(pdocs, 'docId');
     }
 }