diff --git a/README.rdoc b/README.rdoc
index 3e6ede1..6852672 100644
--- a/README.rdoc
+++ b/README.rdoc
@@ -53,6 +53,8 @@ Your global configuration must provide information about your LDAP host to funct
   group_base: # base DN for your LDAP groups, eg ou=Groups,dc=redhat,dc=com
   use_netgroups: # false by default, use true if you want to use netgroup triples,
                  # supported only for server type :free_ipa and :posix
+  use_rfc4519_group_membership: # false by default, use true if you want to use group membership extensions from RFC4519. Typically you may want to use this if your LDAP server is based on 389DS.
+                                # supported only for server type :posix
   server_type: # type of server. default == :posix. :active_directory, :posix, :free_ipa
   ad_domain: # domain for your users if using active directory, eg redhat.com
   service_user: # service account for authenticating LDAP calls. required unless you enable anon
diff --git a/lib/ldap_fluff/config.rb b/lib/ldap_fluff/config.rb
index ef09acc..cc359e2 100644
--- a/lib/ldap_fluff/config.rb
+++ b/lib/ldap_fluff/config.rb
@@ -4,7 +4,7 @@
 class LdapFluff::Config
   ATTRIBUTES = %w[host port encryption base_dn group_base server_type service_user
                   service_pass anon_queries attr_login search_filter
-                  instrumentation_service use_netgroups].freeze
+                  instrumentation_service use_netgroups use_rfc4519_group_membership].freeze
   ATTRIBUTES.each { |attr| attr_reader attr.to_sym }
 
   DEFAULT_CONFIG = { 'port' => 389,
@@ -14,7 +14,8 @@ class LdapFluff::Config
                      'server_type' => :free_ipa,
                      'anon_queries' => false,
                      'instrumentation_service' => nil,
-                     'use_netgroups' => false }.freeze
+                     'use_netgroups' => false,
+                     'use_rfc4519_group_membership' => false }.freeze
 
   def initialize(config)
     raise ArgumentError unless config.respond_to?(:to_hash)
diff --git a/lib/ldap_fluff/generic.rb b/lib/ldap_fluff/generic.rb
index 0bf30d5..0bc3623 100644
--- a/lib/ldap_fluff/generic.rb
+++ b/lib/ldap_fluff/generic.rb
@@ -14,6 +14,7 @@ def initialize(config = {})
     @base       = config.base_dn
     @group_base = (config.group_base.empty? ? config.base_dn : config.group_base)
     @use_netgroups = config.use_netgroups
+    @use_rfc4519_group_membership = config.use_rfc4519_group_membership
     @member_service = create_member_service(config)
   end
 
diff --git a/lib/ldap_fluff/posix.rb b/lib/ldap_fluff/posix.rb
index be5e71b..33f1b25 100644
--- a/lib/ldap_fluff/posix.rb
+++ b/lib/ldap_fluff/posix.rb
@@ -19,10 +19,14 @@ def users_from_search_results(search, method)
     filter = if @use_netgroups
                Net::LDAP::Filter.eq('objectClass', 'nisNetgroup')
              else
-               Net::LDAP::Filter.eq('objectClass', 'posixGroup') |
-                 Net::LDAP::Filter.eq('objectClass', 'organizationalunit') |
-                 Net::LDAP::Filter.eq('objectClass', 'groupOfUniqueNames') |
-                 Net::LDAP::Filter.eq('objectClass', 'groupOfNames')
+               filter = Net::LDAP::Filter.eq('objectClass', 'posixGroup') |
+                        Net::LDAP::Filter.eq('objectClass', 'organizationalunit')
+               if @use_rfc4519_group_membership
+                 filter = filter |
+                          Net::LDAP::Filter.eq('objectClass', 'groupOfUniqueNames') |
+                          Net::LDAP::Filter.eq('objectClass', 'groupOfNames')
+               end
+               filter
              end
     groups = @ldap.search(:base => search.dn, :filter => filter)
     members = groups.map { |group| group.send(method) }.flatten.uniq
diff --git a/lib/ldap_fluff/posix_member_service.rb b/lib/ldap_fluff/posix_member_service.rb
index 0be40c4..72a099d 100644
--- a/lib/ldap_fluff/posix_member_service.rb
+++ b/lib/ldap_fluff/posix_member_service.rb
@@ -4,6 +4,7 @@
 class LdapFluff::Posix::MemberService < LdapFluff::GenericMemberService
   def initialize(ldap, config)
     @attr_login = (config.attr_login || 'memberuid')
+    @use_rfc4519_group_membership = config.use_rfc4519_group_membership
     super
   end
 
@@ -16,8 +17,9 @@ def find_user(uid, base_dn = @base)
   # return an ldap user with groups attached
   # note : this method is not particularly fast for large ldap systems
   def find_user_groups(uid)
+    user = find_user(uid).first
     @ldap.search(
-      :filter => Net::LDAP::Filter.eq('memberuid', uid),
+      :filter => user_group_filter(uid, user[:dn].first),
       :base => @group_base, :attributes => ["cn"]
     ).map { |entry| entry[:cn][0] }
   end
@@ -27,4 +29,17 @@ class UIDNotFoundException < LdapFluff::Error
 
   class GIDNotFoundException < LdapFluff::Error
   end
+
+  private
+
+  def user_group_filter(uid, user_dn)
+    by_member = Net::LDAP::Filter.eq('memberuid', uid)
+    return by_member unless @use_rfc4519_group_membership
+
+    by_name = Net::LDAP::Filter.eq('member', user_dn) &
+              Net::LDAP::Filter.eq('objectClass', 'groupOfNames')
+    by_unique_name = Net::LDAP::Filter.eq('uniquemember', user_dn) &
+                     Net::LDAP::Filter.eq('objectClass', 'groupOfUniqueNames')
+    by_member | by_name | by_unique_name
+  end
 end
diff --git a/test/lib/ldap_test_helper.rb b/test/lib/ldap_test_helper.rb
index 1762513..20c542c 100644
--- a/test/lib/ldap_test_helper.rb
+++ b/test/lib/ldap_test_helper.rb
@@ -121,7 +121,7 @@ def netiq_group_payload
   end
 
   def posix_user_payload
-    [{ :cn => ["john"] }]
+    [{ :cn => ["john"], :dn => ["cn=john,ou=people,dc=internet,dc=com"] }]
   end
 
   def posix_group_payload
diff --git a/test/netiq_test.rb b/test/netiq_test.rb
index c5cc678..d36d796 100644
--- a/test/netiq_test.rb
+++ b/test/netiq_test.rb
@@ -128,9 +128,7 @@ def test_find_users_in_nested_groups
       [nested_group],
       [{ :base => group.dn,
          :filter => Net::LDAP::Filter.eq('objectClass', 'posixGroup') |
-                    Net::LDAP::Filter.eq('objectClass', 'organizationalunit') |
-                    Net::LDAP::Filter.eq('objectClass', 'groupOfUniqueNames') |
-                    Net::LDAP::Filter.eq('objectClass', 'groupOfNames') }])
+                    Net::LDAP::Filter.eq('objectClass', 'organizationalunit') }])
     @netiq.ldap = @ldap
 
     md = Minitest::Mock.new
diff --git a/test/posix_member_services_test.rb b/test/posix_member_services_test.rb
index 2a49fe4..9d3c8b9 100644
--- a/test/posix_member_services_test.rb
+++ b/test/posix_member_services_test.rb
@@ -18,21 +18,54 @@ def test_find_user
   end
 
   def test_find_user_groups
-    user = posix_group_payload
-    @ldap.expect(:search, user, [:filter => @ms.name_filter('john'),
+    group = posix_group_payload
+    user = posix_user_payload
+    username = 'john'
+
+    @ldap.expect(:search, user, [:filter => @ms.name_filter(username),
+                                 :base => config.base_dn])
+    filter = Net::LDAP::Filter.eq('memberuid', username)
+    @ldap.expect(:search, group, [:filter => filter,
                                  :base => config.group_base,
                                  :attributes => ["cn"]])
     @ms.ldap = @ldap
-    assert_equal ['broze'], @ms.find_user_groups('john')
+    assert_equal ['broze'], @ms.find_user_groups(username)
+    @ldap.verify
+  end
+
+  def test_find_user_groups_rfc4519
+    @ms.instance_variable_set('@use_rfc4519_group_membership', true)
+
+    group = posix_group_payload
+    user = posix_user_payload
+    username = 'john'
+
+    @ldap.expect(:search, user, [:filter => @ms.name_filter(username),
+                                 :base => config.base_dn])
+    filter = [Net::LDAP::Filter.eq('memberuid', username),
+              Net::LDAP::Filter.eq('member', user.first[:dn].first) & Net::LDAP::Filter.eq('objectClass', 'groupOfNames'),
+              Net::LDAP::Filter.eq('uniquemember', user.first[:dn].first) & Net::LDAP::Filter.eq('objectClass', 'groupOfUniqueNames')
+             ].reduce(&:|)
+
+    @ldap.expect(:search, group, [:filter => filter,
+                                 :base => config.group_base,
+                                 :attributes => ["cn"]])
+    @ms.ldap = @ldap
+    assert_equal ['broze'], @ms.find_user_groups(username)
     @ldap.verify
   end
 
   def test_find_no_groups
-    @ldap.expect(:search, [], [:filter => @ms.name_filter("john"),
+    user = posix_user_payload
+    username = 'john'
+    @ldap.expect(:search, user, [:filter => @ms.name_filter(username),
+                                 :base => config.base_dn])
+    filter = @ms.send(:user_group_filter, username, user.first[:dn].first)
+    @ldap.expect(:search, [], [:filter => filter,
                                :base => config.group_base,
                                :attributes => ["cn"]])
     @ms.ldap = @ldap
-    assert_equal [], @ms.find_user_groups('john')
+    assert_equal [], @ms.find_user_groups(username)
     @ldap.verify
   end
 
diff --git a/test/posix_test.rb b/test/posix_test.rb
index d95faa8..1448313 100644
--- a/test/posix_test.rb
+++ b/test/posix_test.rb
@@ -119,13 +119,40 @@ def test_find_users_in_nested_groups
     nested_group = Net::LDAP::Entry.new('CN=katellers,CN=foremaners,DC=example,DC=com')
     nested_group[:memberuid] = ['testuser']
 
+    @ldap.expect(:search,
+      [nested_group],
+      [{ :base => group.dn,
+         :filter => Net::LDAP::Filter.eq('objectClass', 'posixGroup') |
+                    Net::LDAP::Filter.eq('objectClass', 'organizationalunit') }])
+    @posix.ldap = @ldap
+
+    md = Minitest::Mock.new
+    2.times { md.expect(:find_group, [group], ['foremaners']) }
+    @posix.member_service = md
+
+    assert_equal @posix.users_for_gid('foremaners'), ['testuser']
+
+    md.verify
+    @ldap.verify
+  end
+
+  def test_find_users_in_nested_groups_with_rfc4519
+    @posix.instance_variable_set('@use_rfc4519_group_membership', true)
+
+    service_bind
+    group = Net::LDAP::Entry.new('CN=foremaners,DC=example,DC=com')
+    group[:memberuid] = ['katellers']
+    nested_group = Net::LDAP::Entry.new('CN=katellers,CN=foremaners,DC=example,DC=com')
+    nested_group[:memberuid] = ['testuser']
+
     @ldap.expect(:search,
       [nested_group],
       [{ :base => group.dn,
          :filter => Net::LDAP::Filter.eq('objectClass', 'posixGroup') |
                     Net::LDAP::Filter.eq('objectClass', 'organizationalunit') |
                     Net::LDAP::Filter.eq('objectClass', 'groupOfUniqueNames') |
-                    Net::LDAP::Filter.eq('objectClass', 'groupOfNames')}])
+                    Net::LDAP::Filter.eq('objectClass', 'groupOfNames')
+       }])
     @posix.ldap = @ldap
 
     md = Minitest::Mock.new