diff --git a/account/views/admin.py b/account/views/admin.py
index 83f4a93e..94af4b9f 100644
--- a/account/views/admin.py
+++ b/account/views/admin.py
@@ -21,22 +21,10 @@ class UserAdminAPI(APIView):
             user = User.objects.get(id=data["id"])
         except User.DoesNotExist:
             return self.error("User does not exist")
-        try:
-            user = User.objects.get(username=data["username"])
-            if user.id != data["id"]:
-                return self.error("Username already exists")
-        except User.DoesNotExist:
-            pass
-
-        try:
-            user = User.objects.get(email=data["email"])
-            if user.id != data["id"]:
-                return self.error("Email already exists")
-        # Some old data has duplicate email
-        except MultipleObjectsReturned:
+        if User.objects.filter(username=data["username"]).exclude(id=user.id).exists():
+            return self.error("Username already exists")
+        if User.objects.filter(email=data["email"].lower()).exclude(id=user.id).exists():
             return self.error("Email already exists")
-        except User.DoesNotExist:
-            pass
 
         user.username = data["username"]
         user.email = data["email"]
diff --git a/announcement/views/admin.py b/announcement/views/admin.py
index 86d54303..58d35780 100644
--- a/announcement/views/admin.py
+++ b/announcement/views/admin.py
@@ -28,13 +28,12 @@ class AnnouncementAdminAPI(APIView):
         """
         data = request.data
         try:
-            announcement = Announcement.objects.get(id=data["id"])
+            announcement = Announcement.objects.get(id=data.pop("id"))
         except Announcement.DoesNotExist:
             return self.error("Announcement does not exist")
 
-        announcement.title = data["title"]
-        announcement.content = data["content"]
-        announcement.visible = data["visible"]
+        for k, v in data.items():
+            setattr(announcement, k, v)
         announcement.save()
 
         return self.success(AnnouncementSerializer(announcement).data)
diff --git a/problem/views/admin.py b/problem/views/admin.py
index 7d1ac676..a7e24db9 100644
--- a/problem/views/admin.py
+++ b/problem/views/admin.py
@@ -8,7 +8,7 @@ from django.conf import settings
 from account.decorators import problem_permission_required
 from contest.models import Contest
 from utils.api import APIView, CSRFExemptAPIView, validate_serializer
-from utils.shortcuts import rand_str
+from utils.shortcuts import rand_str, natural_sort_key
 
 from ..models import Problem, ProblemRuleType, ProblemTag
 from ..serializers import (CreateContestProblemSerializer, ContestProblemAdminSerializer,
@@ -30,7 +30,7 @@ class TestCaseUploadAPI(CSRFExemptAPIView):
                     prefix += 1
                     continue
                 else:
-                    return sorted(ret)
+                    return sorted(ret, key=natural_sort_key)
         else:
             while True:
                 in_name = str(prefix) + ".in"
@@ -41,7 +41,7 @@ class TestCaseUploadAPI(CSRFExemptAPIView):
                     prefix += 1
                     continue
                 else:
-                    return sorted(ret)
+                    return sorted(ret, key=natural_sort_key)
 
     @problem_permission_required
     def post(self, request):
diff --git a/utils/shortcuts.py b/utils/shortcuts.py
index 8fc1ffac..9340564e 100644
--- a/utils/shortcuts.py
+++ b/utils/shortcuts.py
@@ -1,3 +1,4 @@
+import re
 import datetime
 import random
 from base64 import b64encode
@@ -57,3 +58,8 @@ def datetime2str(value, format="iso-8601"):
 
 def timestamp2utcstr(value):
     return datetime.datetime.utcfromtimestamp(value).isoformat()
+
+
+def natural_sort_key(s, _nsre=re.compile(r"(\d+)")):
+    return [int(text) if text.isdigit() else text.lower()
+            for text in re.split(_nsre, s)]