diff --git a/app/assets/stylesheets/specific/posts.css.scss b/app/assets/stylesheets/specific/posts.css.scss
index 9c78725fc..8327bb04b 100644
--- a/app/assets/stylesheets/specific/posts.css.scss
+++ b/app/assets/stylesheets/specific/posts.css.scss
@@ -302,11 +302,19 @@ div#c-post-versions, div#c-artist-versions {
       margin-right: 0.5em;
     }
 
+    ins.obsolete, ins.obsolete a {
+      color: darkGreen;
+    }
+
     del, del a {
       color: red;
       text-decoration: line-through;
       margin-right: 0.5em;
     }
+
+    del.obsolete, del.obsolete a {
+      color: darkRed;
+    }
   }
 }
 
diff --git a/app/helpers/post_versions_helper.rb b/app/helpers/post_versions_helper.rb
index a9ce482d1..cf2e0d9c8 100644
--- a/app/helpers/post_versions_helper.rb
+++ b/app/helpers/post_versions_helper.rb
@@ -5,9 +5,15 @@ module PostVersionsHelper
     diff[:added_tags].each do |tag|
       html << '<ins>+' + link_to(tag, posts_path(:tags => tag)) + '</ins>'
     end
+    diff[:obsolete_added_tags].each do |tag|
+      html << '+<ins class="obsolete">' + link_to(tag, posts_path(:tags => tag)) + '</ins>'
+    end
     diff[:removed_tags].each do |tag|
       html << '<del>-' + link_to(tag, posts_path(:tags => tag)) + '</del>'
     end
+    diff[:obsolete_removed_tags].each do |tag|
+      html << '-<del class="obsolete">' + link_to(tag, posts_path(:tags => tag)) + '</del>'
+    end
     diff[:unchanged_tags].each do |tag|
       html << '<span>' + link_to(tag, posts_path(:tags => tag)) + '</span>'
     end
diff --git a/app/models/post_version.rb b/app/models/post_version.rb
index 1e7dff2e8..ee316ca29 100644
--- a/app/models/post_version.rb
+++ b/app/models/post_version.rb
@@ -84,12 +84,15 @@ class PostVersion < ActiveRecord::Base
       old_tags << "source:#{version.source}" if version.source.present?
     end
 
+    added_tags = new_tags - old_tags
+    removed_tags = old_tags - new_tags
+
     return {
-      :added_tags => new_tags - old_tags,
-      :removed_tags => old_tags - new_tags,
+      :added_tags => added_tags & latest_tags,
+      :removed_tags => removed_tags - latest_tags,
+      :obsolete_added_tags => added_tags - latest_tags,
+      :obsolete_removed_tags => removed_tags & latest_tags,
       :unchanged_tags => new_tags & old_tags,
-      :obsolete_added_tags => new_tags - latest_tags,
-      :obsolete_removed_tags => old_tags & latest_tags,
     }
   end