diff --git a/lib/uuid.rb b/lib/uuid.rb
index dac0af1..3d1f7d7 100644
--- a/lib/uuid.rb
+++ b/lib/uuid.rb
@@ -11,6 +11,7 @@
 require 'tmpdir'
 require 'socket'
 require 'macaddr'
+require 'digest/sha1'
 
 
 ##
@@ -194,6 +195,55 @@ def self.validate(uuid)
       uuid =~ /\A(urn:uuid:)?[\da-f]{8}-([\da-f]{4}-){3}[\da-f]{12}\z/i
   end
 
+  ##
+  # Generate a pseudo MAC address because we have no pure-ruby way
+  # to know  the MAC  address of the  NIC this system  uses.  Note
+  # that cheating  with pseudo arresses here  is completely legal:
+  # see Section 4.5 of RFC4122 for details.
+  #
+  # This implementation is shamelessly stolen from
+  #  https://github.com/spectra/ruby-uuid/blob/master/uuid.rb
+  # Thanks spectra.
+  #
+  def pseudo_mac_address
+    sha1 = ::Digest::SHA1.new
+    256.times do
+      r = [rand(0x100000000)].pack "N"
+      sha1.update r
+    end
+    str = sha1.digest
+    r = rand 14 # 20-6
+    node = str[r, 6] || str
+    if RUBY_VERSION >= "1.9.0"
+      nnode = node.bytes.to_a
+      nnode[0] |= 0x01
+      node = ''
+      nnode.each { |s| node << s.chr }
+    else
+      node[0] |= 0x01 # multicast bit
+    end
+    node.bytes.collect{|b|b.to_s(16)}.join.hex & 0x7FFFFFFFFFFF
+  end
+
+  ##
+  # Uses system calls to get a mac address
+  #
+  def iee_mac_address
+    begin
+      Mac.addr.gsub(/:|-/, '').hex & 0x7FFFFFFFFFFF
+    rescue
+      0 
+    end
+  end
+
+  ##
+  # return iee_mac_address if available, pseudo_mac_address otherwise
+  #
+  def mac_address
+    return iee_mac_address unless iee_mac_address == 0
+    return pseudo_mac_address
+  end
+
   ##
   # Create a new UUID generator.  You really only need to do this once.
   def initialize
@@ -205,8 +255,8 @@ def initialize
     if state_file && File.size?(state_file) then
       next_sequence
     else
-      @mac = Mac.addr.gsub(/:|-/, '').hex & 0x7FFFFFFFFFFF
-      fail "Cannot determine MAC address from any available interface, tried with #{Mac.addr}" if @mac == 0
+      @mac = mac_address
+      fail "Cannot determine MAC address from any available interface, tried with #{mac_address}" if @mac == 0
       @sequence = rand 0x10000
 
       if state_file
diff --git a/test/test-uuid.rb b/test/test-uuid.rb
index c4ea1c9..d28ce5f 100644
--- a/test/test-uuid.rb
+++ b/test/test-uuid.rb
@@ -4,6 +4,7 @@
 # License:: MIT and/or Creative Commons Attribution-ShareAlike
 
 require 'test/unit'
+require 'rubygems'
 require 'uuid'
 
 class TestUUID < Test::Unit::TestCase
@@ -31,8 +32,7 @@ def test_with_no_state_file
     assert !UUID.state_file
   end
 
-  def test_instance_generate
-    uuid = UUID.new
+  def validate_uuid_generator(uuid)
     assert_match(/\A[\da-f]{32}\z/i, uuid.generate(:compact))
 
     assert_match(/\A[\da-f]{8}-[\da-f]{4}-[\da-f]{4}-[\da-f]{4}-[\da-f]{12}\z/i,
@@ -44,8 +44,13 @@ def test_instance_generate
     e = assert_raise ArgumentError do
       uuid.generate :unknown
     end
-
     assert_equal 'invalid UUID format :unknown', e.message
+
+  end
+
+  def test_instance_generate
+    uuid = UUID.new
+    validate_uuid_generator(uuid)
   end
 
   def test_class_generate
@@ -108,5 +113,15 @@ class << bar = UUID.new
     assert_equal foo.sequence + 1, bar.sequence
   end
 
+  def test_pseudo_random_mac_address
+    uuid_gen = UUID.new
+    def Mac.addr; '00:00:00:00:00:00'; end
+    assert uuid_gen.iee_mac_address == 0
+    [:compact, :default, :urn].each do |format|
+      assert UUID.validate(uuid_gen.generate(format)), format.to_s
+    end
+    validate_uuid_generator(uuid_gen)
+  end
+
 end