diff --git a/lib/api/helpers/attachment_renderer.rb b/lib/api/helpers/attachment_renderer.rb
index 5ae693317f..49fbe4d4ff 100644
--- a/lib/api/helpers/attachment_renderer.rb
+++ b/lib/api/helpers/attachment_renderer.rb
@@ -43,7 +43,7 @@ module API
           redirect attachment.external_url.to_s
         else
           content_type attachment.content_type
-          header['Content-Disposition'] = attachment.content_disposition
+          header['Content-Disposition'] = "#{attachment.content_disposition}; filename=#{attachment.filename}"
           env['api.format'] = :binary
           attachment.diskfile.read
         end
diff --git a/spec/requests/api/v3/attachments/attachment_resource_shared_examples.rb b/spec/requests/api/v3/attachments/attachment_resource_shared_examples.rb
index ccace9fe91..a67429ddf8 100644
--- a/spec/requests/api/v3/attachments/attachment_resource_shared_examples.rb
+++ b/spec/requests/api/v3/attachments/attachment_resource_shared_examples.rb
@@ -287,14 +287,14 @@ shared_examples 'an APIv3 attachment resource', type: :request, content_type: :j
       context 'for a local text file' do
         it_behaves_like 'for a local file' do
           let(:mock_file) { FileHelpers.mock_uploaded_file name: 'foobar.txt' }
-          let(:content_disposition) { "inline" }
+          let(:content_disposition) { "inline; filename=foobar.txt" }
         end
       end
 
       context 'for a local binary file' do
         it_behaves_like 'for a local file' do
           let(:mock_file) { FileHelpers.mock_uploaded_file name: 'foobar.dat', content_type: "application/octet-stream" }
-          let(:content_disposition) { "attachment" }
+          let(:content_disposition) { "attachment; filename=foobar.dat" }
         end
       end