diff --git a/src/model/users.ts b/src/model/users.ts
index eed2dda..7a1a8ff 100644
--- a/src/model/users.ts
+++ b/src/model/users.ts
@@ -500,10 +500,8 @@ export default class Users {
     tr: Transaction,
     userIdx: number,
   ): Promise<Array<string>> {
-    const query = 'SELECT sn.student_number FROM users u '
-      + 'LEFT OUTER JOIN student_numbers AS sn ON sn.owner_idx = u.idx '
-      + 'WHERE u.idx = $1';
-    const result = await tr.query<{ idx: number; student_number: string }>(query, [userIdx]);
+    const query = 'SELECT student_number FROM student_numbers WHERE owner_idx = $1';
+    const result = await tr.query<{ student_number: string }>(query, [userIdx]);
     return result.rows.map(row => row.student_number);
   }
 
@@ -511,9 +509,8 @@ export default class Users {
     tr: Transaction,
     userIndices: Array<number>,
   ): Promise<Map<number, Array<string>>> {
-    const query = 'SELECT u.idx, sn.student_number FROM users u '
-      + 'LEFT OUTER JOIN student_numbers AS sn ON sn.owner_idx = u.idx '
-      + 'WHERE u.idx = ANY($1)';
+    const query = 'SELECT owner_idx as idx, student_number FROM student_numbers '
+      + 'WHERE owner_idx = ANY($1)';
     const result = await tr.query<{ idx: number; student_number: string }>(query, [userIndices]);
     const map = new Map<number, Array<string>>();
     for (const row of result.rows) {
diff --git a/test/api/groups.test.ts b/test/api/groups.test.ts
index 5496ff4..442b602 100644
--- a/test/api/groups.test.ts
+++ b/test/api/groups.test.ts
@@ -109,7 +109,6 @@ test('member listing', async t => {
   let memberUserIdx = 0;
   await model.pgDo(async tr => {
     memberUserIdx = await createUser(tr, model);
-    await model.users.addStudentNumber(tr, memberUserIdx, uuid());
     await model.users.addUserMembership(tr, memberUserIdx, groupIdx);
   }, ['users']);
 
@@ -117,6 +116,16 @@ test('member listing', async t => {
   t.is(response.status, 200);
   t.is(response.body.length, 1);
   t.is(response.body[0].uid, memberUserIdx);
+  t.deepEqual(response.body[0].studentNumbers, []);
+
+  const studentNumber = uuid();
+  await model.pgDo(tr => model.users.addStudentNumber(tr, memberUserIdx, studentNumber), ['users']);
+
+  response = await agent.get(`/api/group/${groupIdx}/members`);
+  t.is(response.status, 200);
+  t.is(response.body.length, 1);
+  t.is(response.body[0].uid, memberUserIdx);
+  t.deepEqual(response.body[0].studentNumbers, [studentNumber]);
 });
 
 test('pending listing', async t => {
@@ -157,7 +166,6 @@ test('pending listing', async t => {
   let pendingUserIdx = 0;
   await model.pgDo(async tr => {
     pendingUserIdx = await createUser(tr, model);
-    await model.users.addStudentNumber(tr, pendingUserIdx, uuid());
     await model.users.addPendingUserMembership(tr, pendingUserIdx, groupIdx);
   }, ['users']);
 
@@ -165,6 +173,18 @@ test('pending listing', async t => {
   t.is(response.status, 200);
   t.is(response.body.length, 1);
   t.is(response.body[0].uid, pendingUserIdx);
+  t.deepEqual(response.body[0].studentNumbers, []);
+
+  const studentNumber = uuid();
+  await model.pgDo(tr => model.users.addStudentNumber(tr, pendingUserIdx, studentNumber), [
+    'users',
+  ]);
+
+  response = await agent.get(`/api/group/${groupIdx}/pending`);
+  t.is(response.status, 200);
+  t.is(response.body.length, 1);
+  t.is(response.body[0].uid, pendingUserIdx);
+  t.deepEqual(response.body[0].studentNumbers, [studentNumber]);
 });
 
 test('apply to group', async t => {