diff --git a/app/models/post.rb b/app/models/post.rb
index 31b994ba6..e098aa846 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -402,7 +402,7 @@ class Post < ApplicationRecord
     end
 
     def add_automatic_tags(tags)
-      tags -= %w[incredibly_absurdres absurdres highres lowres flash video ugoira animated_gif animated_png exif_rotation non-repeating_animation non-web_source wide_image tall_image sound]
+      tags -= %w[incredibly_absurdres absurdres highres lowres flash video ugoira animated_gif animated_png exif_rotation non-repeating_animation non-web_source wide_image tall_image]
 
       if tags.size >= 30
         tags -= ["tagme"]
@@ -472,6 +472,9 @@ class Post < ApplicationRecord
       tags << "exif_rotation" if media_asset.is_rotated?
       tags << "non-repeating_animation" if media_asset.is_non_repeating_animation?
       tags << "ai-generated" if media_asset.is_ai_generated?
+
+      # Allow Flash files to be manually tagged as `sound`; other files are automatically tagged.
+      tags -= ["sound"] unless is_flash?
       tags << "sound" if media_asset.has_sound?
 
       tags
diff --git a/test/unit/post_test.rb b/test/unit/post_test.rb
index 3a2fa57d0..448eb206f 100644
--- a/test/unit/post_test.rb
+++ b/test/unit/post_test.rb
@@ -1269,7 +1269,7 @@ class PostTest < ActiveSupport::TestCase
           @media_asset = MediaAsset.upload!("test/files/mp4/test-silent-audio.mp4")
           @post.update!(md5: @media_asset.md5)
           @post.reload.update!(tag_string: "sound")
-          assert_equal("animated tagme", @post.tag_string)
+          assert_equal("animated", @post.tag_string)
         end
       end
 
@@ -1282,6 +1282,15 @@ class PostTest < ActiveSupport::TestCase
         end
       end
 
+      context "a Flash file with the sound tag" do
+        should "not automatically remove the sound tag" do
+          @post = create(:post, file_ext: "swf", media_asset: build(:media_asset, file_ext: "swf"))
+          @post.update!(tag_string: "sound")
+
+          assert_equal("flash sound", @post.tag_string)
+        end
+      end
+
       context "a post with a non-web source" do
         should "automatically add the non-web_source tag" do
           @post.update!(source: "this was once revealed to me in a dream")