diff --git a/app/views/attachments/_form.html.erb b/app/views/attachments/_form.html.erb
index 96c8c6476..6dd07a9d4 100644
--- a/app/views/attachments/_form.html.erb
+++ b/app/views/attachments/_form.html.erb
@@ -30,6 +30,7 @@
         :multiple => multiple,
         :onchange => 'addInputFiles(this);',
         :data => {
+          :max_number_of_files_message => l(:error_attachments_too_many, :max_number_of_files => 10),
           :max_file_size => Setting.attachment_max_size.to_i.kilobytes,
           :max_file_size_message => l(:error_attachment_too_big, :max_size => number_to_human_size(Setting.attachment_max_size.to_i.kilobytes)),
           :max_concurrent_uploads => Redmine::Configuration['max_concurrent_ajax_uploads'].to_i,
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 2b4850c05..efaea5252 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -213,6 +213,7 @@ en:
   error_workflow_copy_target: 'Please select target tracker(s) and role(s)'
   error_unable_delete_issue_status: 'Unable to delete issue status (%{value})'
   error_unable_to_connect: "Unable to connect (%{value})"
+  error_attachments_too_many: "This file cannot be uploaded because it exceeds the maximum number of files that can be attached simultaneously (%{max_number_of_files})"
   error_attachment_too_big: "This file cannot be uploaded because it exceeds the maximum allowed file size (%{max_size})"
   error_bulk_download_size_too_big: "These attachments cannot be bulk downloaded because the total file size exceeds the maximum allowed size (%{max_size})"
   error_session_expired: "Your session has expired. Please login again."
diff --git a/public/javascripts/attachments.js b/public/javascripts/attachments.js
index 402cfa53f..567b6be81 100644
--- a/public/javascripts/attachments.js
+++ b/public/javascripts/attachments.js
@@ -29,6 +29,8 @@ function addFile(inputEl, file, eagerUpload) {
 
     addAttachment.toggle(attachmentsFields.children().length < maxFiles);
     return attachmentId;
+  } else {
+    alert($('input.file_selector').data('max-number-of-files-message'));
   }
   return null;
 }