diff --git a/judge/admin/__init__.py b/judge/admin/__init__.py
index 67c778c..0414d58 100644
--- a/judge/admin/__init__.py
+++ b/judge/admin/__init__.py
@@ -15,6 +15,7 @@ from judge.models import BlogPost, Comment, CommentLock, Contest, ContestPartici
     ContestTag, Judge, Language, License, MiscConfig, NavigationBar, Organization, \
     OrganizationRequest, Problem, ProblemGroup, ProblemPointsVote, ProblemType, Profile, Submission, Ticket
 
+
 admin.site.register(BlogPost, BlogPostAdmin)
 admin.site.register(Comment, CommentAdmin)
 admin.site.register(CommentLock)
@@ -36,4 +37,3 @@ admin.site.register(ProblemType, ProblemTypeAdmin)
 admin.site.register(Profile, ProfileAdmin)
 admin.site.register(Submission, SubmissionAdmin)
 admin.site.register(Ticket, TicketAdmin)
-admin.site
diff --git a/judge/admin/contest.py b/judge/admin/contest.py
index 8678281..bda5156 100644
--- a/judge/admin/contest.py
+++ b/judge/admin/contest.py
@@ -11,6 +11,7 @@ from django.utils import timezone
 from django.utils.html import format_html
 from django.utils.translation import gettext_lazy as _, ungettext
 from reversion.admin import VersionAdmin
+from reversion_compare.admin import CompareVersionAdmin
 
 from django_ace import AceWidget
 from judge.models import Contest, ContestProblem, ContestSubmission, Profile, Rating
@@ -113,7 +114,7 @@ class ContestForm(ModelForm):
             widgets['description'] = HeavyPreviewAdminPageDownWidget(preview=reverse_lazy('contest_preview'))
 
 
-class ContestAdmin(VersionAdmin):
+class ContestAdmin(CompareVersionAdmin):
     fieldsets = (
         (None, {'fields': ('key', 'name', 'authors', 'curators', 'testers')}),
         (_('Settings'), {'fields': ('is_visible', 'use_clarifications', 'hide_problem_tags', 'scoreboard_visibility',
diff --git a/judge/admin/interface.py b/judge/admin/interface.py
index 4691c8b..fb57844 100644
--- a/judge/admin/interface.py
+++ b/judge/admin/interface.py
@@ -6,6 +6,8 @@ from django.utils.html import format_html
 from django.utils.translation import gettext_lazy as _
 from mptt.admin import DraggableMPTTAdmin
 from reversion.admin import VersionAdmin
+from reversion_compare.admin import CompareVersionAdmin
+
 
 from judge.dblock import LockModel
 from judge.models import NavigationBar
@@ -58,7 +60,7 @@ class BlogPostForm(ModelForm):
             widgets['summary'] = HeavyPreviewAdminPageDownWidget(preview=reverse_lazy('blog_preview'))
 
 
-class BlogPostAdmin(VersionAdmin):
+class BlogPostAdmin(CompareVersionAdmin):
     fieldsets = (
         (None, {'fields': ('title', 'slug', 'authors', 'visible', 'sticky', 'publish_on',
                            'is_organization_private', 'organizations')}),
@@ -121,7 +123,7 @@ class UserListFilter(admin.SimpleListFilter):
 
 class LogEntryAdmin(admin.ModelAdmin):
     readonly_fields = ('user', 'content_type', 'object_id', 'object_repr', 'action_flag', 'change_message')
-    list_display = ('__str__', 'action_time', 'user', 'content_type', 'object_link')
+    list_display = ('__str__', 'action_time', 'user', 'content_type', 'object_link', 'diff_link')
     search_fields = ('object_repr', 'change_message')
     list_filter = (UserListFilter, 'content_type')
     list_display_links = None
@@ -150,5 +152,17 @@ class LogEntryAdmin(admin.ModelAdmin):
     object_link.admin_order_field = 'object_repr'
     object_link.short_description = _('object')
 
+    def diff_link(self, obj):
+        if obj.is_deletion():
+            return None
+        ct = obj.content_type
+        try:
+            url = reverse('admin:%s_%s_history' % (ct.app_label, ct.model), args=(obj.object_id,))
+            link = format_html('<a href="{1}">{0}</a>', _('Diff'), url)
+        except NoReverseMatch:
+            link = None
+        return link
+    diff_link.short_description = _('diff')
+
     def queryset(self, request):
         return super().queryset(request).prefetch_related('content_type')
diff --git a/judge/models/__init__.py b/judge/models/__init__.py
index c9c5db2..2518bc2 100644
--- a/judge/models/__init__.py
+++ b/judge/models/__init__.py
@@ -31,4 +31,6 @@ revisions.register(ProblemPointsVote)
 revisions.register(ContestMoss)
 revisions.register(ProblemData)
 revisions.register(ProblemTestCase)
+revisions.register(ContestParticipation)
+revisions.register(Rating)
 del revisions