diff --git a/config/initializers/paperclip.rb b/config/initializers/paperclip.rb
index 392784c53..c02f3afec 100644
--- a/config/initializers/paperclip.rb
+++ b/config/initializers/paperclip.rb
@@ -13,26 +13,32 @@ Paperclip::Attachment.default_options.merge!(
 
 Paperclip::UriAdapter.register
 
-if ENV['PAPERCLIP_STORAGE'] == "s3"
-
-  if ENV['S3_BUCKET'].nil? or ENV['AWS_REGION'].nil? or
-    ENV['AWS_ACCESS_KEY_ID'].nil? or ENV['AWS_SECRET_ACCESS_KEY'].nil?
-    puts "WARNING! Environment variables S3_BUCKET, AWS_REGION, " +
-         "AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY must be set."
+if ENV['PAPERCLIP_STORAGE'] == 's3'
+  if ENV['S3_BUCKET'].nil? || ENV['AWS_REGION'].nil? ||
+     ENV['AWS_ACCESS_KEY_ID'].nil? || ENV['AWS_SECRET_ACCESS_KEY'].nil?
+    puts 'WARNING! Environment variables S3_BUCKET, AWS_REGION, '\
+         'AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY must be set.'
     exit 1
   end
-  Paperclip::Attachment.default_options.merge!({
+
+  s3_credentials = { bucket: ENV['S3_BUCKET'] }
+
+  if ENV['AWS_ACCESS_KEY_ID'] && ENV['AWS_SECRET_ACCESS_KEY']
+    s3_credentials[:access_key_id] = ENV['AWS_ACCESS_KEY_ID']
+    s3_credentials[:secret_access_key] = ENV['AWS_SECRET_ACCESS_KEY']
+  end
+
+  s3_path = '/:class/:attachment/:id_partition/:hash/:style/:filename'
+  s3_path.prepend("/#{ENV['S3_SUBFOLDER']}") if ENV['S3_SUBFOLDER']
+
+  Paperclip::Attachment.default_options.merge!(
     url: ':s3_domain_url',
-    path: '/:class/:attachment/:id_partition/:hash/:style/:filename',
+    path: s3_path,
     storage: :s3,
     s3_region: ENV['AWS_REGION'],
     s3_host_name: "s3.#{ENV['AWS_REGION']}.amazonaws.com",
     s3_protocol: 'https',
-    s3_credentials: {
-      bucket: ENV['S3_BUCKET'],
-      access_key_id: ENV['AWS_ACCESS_KEY_ID'],
-      secret_access_key: ENV['AWS_SECRET_ACCESS_KEY']
-    },
+    s3_credentials: s3_credentials,
     s3_permissions: {
       original: :private,
       medium: :private
@@ -43,12 +49,9 @@ if ENV['PAPERCLIP_STORAGE'] == "s3"
       icon: :REDUCED_REDUNDANCY,
       icon_small: :REDUCED_REDUNDANCY
     }
-  })
-elsif ENV['PAPERCLIP_STORAGE'] == "filesystem"
-  Paperclip::Attachment.default_options.merge!({
-    storage: :filesystem
-  })
-
+  )
+elsif ENV['PAPERCLIP_STORAGE'] == 'filesystem'
+  Paperclip::Attachment.default_options[:storage] = :filesystem
 end
 
 Paperclip::Attachment.class_eval do