diff --git a/app/models/message/searchable.rb b/app/models/message/searchable.rb
index e827c61..2cfe696 100644
--- a/app/models/message/searchable.rb
+++ b/app/models/message/searchable.rb
@@ -3,7 +3,8 @@ module Message::Searchable
 
   included do
     after_create_commit  :create_in_index
-    after_update_commit  :update_in_index, if: :body_saved?
+    before_update        -> { @attachment_replaced = attachment_changes.key?("attachment") }
+    after_update_commit  :update_in_index, if: :indexed_text_changed?
     after_destroy_commit :remove_from_index
 
     scope :search, ->(query) { joins("join message_search_index idx on messages.id = idx.rowid").where("idx.body match ?", match_terms(query)).ordered }
@@ -22,9 +23,10 @@ module Message::Searchable
       execute_sql_with_binds "insert into message_search_index(rowid, body) values (?, ?)", id, plain_text_body
     end
 
-    # Boosts touch their message too: rewrite the index only when the body was saved.
-    def body_saved?
-      association(:rich_text_body).target&.saved_change_to_body?
+    # Boosts touch their message too: rewrite the index only when the body was saved or the attachment replaced.
+    # Active Storage clears attachment_changes in its own after_commit, before this one runs.
+    def indexed_text_changed?
+      association(:rich_text_body).target&.saved_change_to_body? || @attachment_replaced
     end
 
     def update_in_index
diff --git a/test/models/message/searchable_test.rb b/test/models/message/searchable_test.rb
index 3da41dd..eab5f73 100644
--- a/test/models/message/searchable_test.rb
+++ b/test/models/message/searchable_test.rb
@@ -37,6 +37,14 @@ class Message::SearchableTest < ActiveSupport::TestCase
     assert_equal [], rooms(:designers).messages.search("sharks")
   end
 
+  test "a new attachment replaces the old file name in the index" do
+    message = rooms(:designers).messages.create! attachment: fixture_file_upload("moon.jpg", "image/jpeg"), client_message_id: "moon", creator: users(:david)
+
+    Message.find(message.id).update! attachment: fixture_file_upload("pixel.bmp", "image/bmp")
+    assert_equal [ message ], rooms(:designers).messages.search("pixel")
+    assert_equal [], rooms(:designers).messages.search("moon")
+  end
+
   test "search results are returned in message order" do
     messages = [ "first cat", "second cat", "third cat", "cat cat cat" ].map do |body|
       rooms(:designers).messages.create! body: body, client_message_id: body, creator: users(:david)