diff --git a/Gemfile b/Gemfile
index 4a4797b9..1c072626 100644
--- a/Gemfile
+++ b/Gemfile
@@ -53,6 +53,7 @@ gem 'spreadsheet'
 gem 'exception_notification'
 gem 'gaffe'
 gem 'ruby-filemagic'
+gem 'mime-types'
 gem 'midi-smtp-server'
 
 # we use the git version of acts_as_versioned, and need to include it in this Gemfile
diff --git a/Gemfile.lock b/Gemfile.lock
index 29fbcf07..abd43f65 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -534,6 +534,7 @@ DEPENDENCIES
   mailcatcher
   meta_request
   midi-smtp-server
+  mime-types
   mysql2 (~> 0.4.0)
   prawn
   prawn-table