diff --git a/CHANGELOG.yml b/CHANGELOG.yml
index 0b6bb0a..0d65cf5 100644
--- a/CHANGELOG.yml
+++ b/CHANGELOG.yml
@@ -1,3 +1,5 @@
+0,3,1:
+  - correct comportement when `ActiveStorage::Attached::Many` is given as paramter
 0.3.0:
   - correct subfolders creation (and break some methods signature)
 0.2.0:
diff --git a/Gemfile b/Gemfile
index 1eb9c87..da43cfa 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,6 +5,6 @@ git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 # Specify your gem's dependencies in active_storage-send_zip.gemspec
 gemspec
 
-gem "rails", "~> 5.2"
+gem "rails", "> 5.2"
 
 gem "rubyzip", "~> 1.2"
diff --git a/Gemfile.lock b/Gemfile.lock
index cf20eb4..2fd1886 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    active_storage-send_zip (0.2.0)
+    active_storage-send_zip (0.3.1)
 
 GEM
   remote: https://rubygems.org/
@@ -122,9 +122,9 @@ DEPENDENCIES
   active_storage-send_zip!
   bundler (~> 1.17)
   minitest (~> 5.0)
-  rails (~> 5.2)
+  rails (> 5.2)
   rake (~> 10.0)
   rubyzip (~> 1.2)
 
 BUNDLED WITH
-   1.17.1
+   1.17.2
diff --git a/lib/active_storage/send_zip/version.rb b/lib/active_storage/send_zip/version.rb
index e522d55..2a2cb80 100644
--- a/lib/active_storage/send_zip/version.rb
+++ b/lib/active_storage/send_zip/version.rb
@@ -1,6 +1,6 @@
 module ActiveStorage
   module SendZip
     # The version of this gem
-    VERSION = '0.3.0'.freeze
+    VERSION = '0.3.1'.freeze
   end
 end
diff --git a/lib/active_storage/send_zip_helper.rb b/lib/active_storage/send_zip_helper.rb
index c5702f6..37a6049 100644
--- a/lib/active_storage/send_zip_helper.rb
+++ b/lib/active_storage/send_zip_helper.rb
@@ -9,16 +9,14 @@ module ActiveStorage
   module SendZipHelper
     # Download active storage files on server in a temporary folder
     #
-    # @param files [ActiveStorage::Attached::Many] files to save
+    # @param files [ActiveStorage::Attached::One|ActiveStorage::Attached::Many|Array|Hash] file(s) to save
     # @return [String] folder path of saved files
     def self.save_files_on_server(files)
       require 'zip'
       # get a temporary folder and create it
       temp_folder = Dir.mktmpdir 'active_storage-send_zip'
 
-      if files.is_a? Array
-        files.each { |file| save_file_on_server(file, temp_folder) }
-      elsif files.is_a? Hash
+      if files.is_a? Hash
         filepaths = []
 
         files.each do |subfolder, filesHash|
@@ -27,6 +25,10 @@ def self.save_files_on_server(files)
             filepaths << save_file_on_server(f, temp_folder, subfolder: subfolder.to_s)
           end
         end
+      elsif files.respond_to? :each
+        files.each { |file| save_file_on_server(file, temp_folder) }
+      else
+        raise ArgumentError, '`files` must be an hash or an iterable object'
       end
 
       temp_folder
diff --git a/test/active_storage/send_zip_helper_test.rb b/test/active_storage/send_zip_helper_test.rb
index 2247fe7..d9b55e2 100644
--- a/test/active_storage/send_zip_helper_test.rb
+++ b/test/active_storage/send_zip_helper_test.rb
@@ -54,6 +54,12 @@ def test_it_should_save_files_in_differents_folders
     assert_produce_nested_files files, folder_count: 2, files_count: 3
   end
 
+  def test_it_should_raise_an_exception
+    assert_raises ArgumentError do
+      ActiveStorage::SendZipHelper.save_files_on_server 'bad boi'
+    end
+  end
+
   def test_it_should_save_files_in_differents_folders_with_root_files
     files = {
       'folder A' => [