diff --git a/lib/vagrant/util/mime.rb b/lib/vagrant/util/mime.rb
index c528ef75c..667402747 100644
--- a/lib/vagrant/util/mime.rb
+++ b/lib/vagrant/util/mime.rb
@@ -6,31 +6,38 @@ module Vagrant
     module Mime
       class Multipart
 
+        # @return [Array<String>] collection of content part of the multipart mime
         attr_accessor :content
 
+        # @return [String] type of the content
         attr_accessor :content_type
 
+        # @return [Hash] headers for the mime
         attr_accessor :headers
 
-        attr_accessor :mime_version
-
-        def initialize(content_type="multipart/mixed", mime_version="1.0")
-          @content_id = "#{SecureRandom.alphanumeric(24)}@#{SecureRandom.alphanumeric(24)}.local"
+        # @param [String] (optional) mime content type
+        # @param [String] (optional) mime version
+        def initialize(content_type="multipart/mixed")
+          @content_id = "#{Time.now.to_i}@#{SecureRandom.alphanumeric(24)}.local"
           @boundary = "Boundary_#{SecureRandom.alphanumeric(24)}"
           @content_type = MIME::Types[content_type].first
           @content = []
-          @mime_version = mime_version 
           @headers = {
             "Content-ID"=> "<#{@content_id}>",
             "Content-Type"=> "#{content_type}; boundary=#{@boundary}",
           }
         end
 
+        # Add an entry to the multipart mime
+        #
+        # @param entry to add
         def add(entry)
           content << entry
         end
 
         # Output MimeEntity as a string
+        #
+        # @return [String] mime data
         def to_s
           output_string = ""
           headers.each do |k, v|
@@ -47,19 +54,26 @@ module Vagrant
 
       class Entity
 
+        # @return [String] entity content 
         attr_reader :content
 
+        # @return [String] type of the entity content
         attr_reader :content_type
 
+        # @param [String] entity content
+        # @param [String] type of the entity content
         def initialize(content, content_type)
           if !MIME::Types.include?(content_type)
             MIME::Types.add(MIME::Type.new(content_type))
           end
           @content = content
           @content_type = MIME::Types[content_type].first
-          @content_id = "#{SecureRandom.alphanumeric(24)}@#{SecureRandom.alphanumeric(24)}.local"
+          @content_id = "#{Time.now.to_i}@#{SecureRandom.alphanumeric(24)}.local"
         end
 
+        # Output MimeEntity as a string
+        #
+        # @return [String] mime data
         def to_s
           output_string = "Content-ID: <#{@content_id}>\n"
           output_string += "Content-Type: #{@content_type}\n\n"
diff --git a/test/unit/vagrant/util/mime_test.rb b/test/unit/vagrant/util/mime_test.rb
new file mode 100644
index 000000000..a2dfdfb87
--- /dev/null
+++ b/test/unit/vagrant/util/mime_test.rb
@@ -0,0 +1,85 @@
+require File.expand_path("../../../base", __FILE__)
+
+require 'vagrant/util/mime'
+require 'mime/types'
+
+describe Vagrant::Util::Mime::Multipart do
+
+  subject { described_class }
+
+  let(:time) { 603907018 }
+  let(:secure_random) { "123qwe" }
+
+  before do 
+    allow(Time).to receive(:now).and_return(time)
+    allow(SecureRandom).to receive(:alphanumeric).and_return(secure_random)
+  end
+
+  it "can add headers" do
+    mime = subject.new()
+    mime.headers["Mime-Version"] = "1.0"
+    expected_string = "Content-ID: <#{time}@#{secure_random}.local>
+Content-Type: multipart/mixed; boundary=Boundary_#{secure_random}
+Mime-Version: 1.0
+
+--Boundary_#{secure_random}
+"
+    expect(mime.to_s).to eq(expected_string)
+  end
+
+  it "can add content" do
+    mime = subject.new()
+    mime.add("something")
+    expected_string = "Content-ID: <#{time}@#{secure_random}.local>
+Content-Type: multipart/mixed; boundary=Boundary_#{secure_random}
+
+--Boundary_#{secure_random}
+something
+--Boundary_#{secure_random}
+"
+    expect(mime.to_s).to eq(expected_string)
+  end
+
+  it "can add Vagrant::Util::Mime::Entity content" do
+    mime = subject.new()
+    mime.add(Vagrant::Util::Mime::Entity.new("something", "text/cloud-config"))
+    expected_string = "Content-ID: <#{time}@#{secure_random}.local>
+Content-Type: multipart/mixed; boundary=Boundary_#{secure_random}
+
+--Boundary_#{secure_random}
+Content-ID: <#{time}@#{secure_random}.local>
+Content-Type: text/cloud-config
+
+something
+--Boundary_#{secure_random}
+"
+    expect(mime.to_s).to eq(expected_string)
+  end
+end
+
+describe Vagrant::Util::Mime::Entity do
+
+  subject { described_class }
+
+  let(:time) { 603907018 }
+  let(:secure_random) { "123qwe" }
+
+  before do 
+    allow(Time).to receive(:now).and_return(time)
+    allow(SecureRandom).to receive(:alphanumeric).and_return(secure_random)
+  end
+
+  it "registers the content type" do 
+    subject.new("something", "text/cloud-config")
+    expect(MIME::Types).to include("text/cloud-config")
+  end
+
+  it "outputs as a string" do
+    entity = subject.new("something", "text/cloud-config")
+    expected_string = "Content-ID: <#{time}@#{secure_random}.local>
+Content-Type: text/cloud-config
+
+something"
+    expect(entity.to_s).to eq(expected_string)
+  end
+end