diff --git a/lib/mongo/db.rb b/lib/mongo/db.rb
index b53c337..a8551fd 100644
--- a/lib/mongo/db.rb
+++ b/lib/mongo/db.rb
@@ -161,7 +161,7 @@ module XGen
           auth['authenticate'] = 1
           auth['user'] = username
           auth['nonce'] = nonce
-          auth['key'] = Digest::MD5.hexdigest("#{nonce}#{username}#{hash_password(password)}")
+          auth['key'] = Digest::MD5.hexdigest("#{nonce}#{username}#{hash_password(username, password)}")
           ok?(db_command(auth))
         end
 
@@ -461,8 +461,8 @@ module XGen
 
         private
 
-        def hash_password(plaintext)
-          Digest::MD5.hexdigest("mongo#{plaintext}")
+        def hash_password(username, plaintext)
+          Digest::MD5.hexdigest("#{username}:mongo:#{plaintext}")
         end
 
       end
diff --git a/mongo-ruby-driver.gemspec b/mongo-ruby-driver.gemspec
index 315259c..6bf3c67 100644
--- a/mongo-ruby-driver.gemspec
+++ b/mongo-ruby-driver.gemspec
@@ -1,6 +1,6 @@
 Gem::Specification.new do |s|
   s.name = 'mongo'
-  s.version = '0.4.2'
+  s.version = '0.4.3'
   s.platform = Gem::Platform::RUBY
   s.summary = 'Simple pure-Ruby driver for the 10gen Mongo DB'
   s.description = 'A pure-Ruby driver for the 10gen Mongo DB. For more information about Mongo, see http://www.mongodb.org.'
diff --git a/tests/test_db.rb b/tests/test_db.rb
index f8d5ff4..4f0ba80 100644
--- a/tests/test_db.rb
+++ b/tests/test_db.rb
@@ -24,7 +24,7 @@ class DBTest < Test::Unit::TestCase
     @spongebob_password = 'squarepants'
     @users = @db.collection('system.users')
     @users.clear
-    @users.insert(:user => @spongebob, :pwd => @db.send(:hash_password, @spongebob_password))
+    @users.insert(:user => @spongebob, :pwd => @db.send(:hash_password, @spongebob, @spongebob_password))
   end
 
   def teardown