diff --git a/lib/ldap/group.rb b/lib/ldap/group.rb
index a1c5419f4..e92aa58ad 100644
--- a/lib/ldap/group.rb
+++ b/lib/ldap/group.rb
@@ -112,7 +112,7 @@ class Ldap
     #
     # @return [String, nil] The active or found filter or nil if none could be found.
     def filter
-      @filter ||= lookup_filter(['(objectClass=group)', '(objectClass=posixgroup)', '(objectClass=organization)'])
+      @filter ||= lookup_filter(['(objectClass=groupOfUniqueNames)', '(objectClass=group)', '(objectClass=posixgroup)', '(objectClass=organization)'])
     end
 
     # The active uid attribute of the instance. If none give on initialization an automatic lookup is performed.
diff --git a/spec/sequencer/unit/import/common/model/reset_primary_key_sequence_spec.rb b/spec/lib/sequencer/unit/import/common/model/reset_primary_key_sequence_spec.rb
similarity index 100%
rename from spec/sequencer/unit/import/common/model/reset_primary_key_sequence_spec.rb
rename to spec/lib/sequencer/unit/import/common/model/reset_primary_key_sequence_spec.rb
diff --git a/spec/lib/sequencer/unit/import/ldap/user/mapping_spec.rb b/spec/lib/sequencer/unit/import/ldap/user/mapping_spec.rb
new file mode 100644
index 000000000..8ec256d92
--- /dev/null
+++ b/spec/lib/sequencer/unit/import/ldap/user/mapping_spec.rb
@@ -0,0 +1,27 @@
+require 'rails_helper'
+
+RSpec.describe Sequencer::Unit::Import::Ldap::User::Mapping, sequencer: :unit do
+
+  it 'ensures to unset attribute value if none is provided' do
+
+    ldap_config = {
+      user_attributes: {
+        firstName:      'firstname',
+        lastName:       'lastname',
+        samaccountname: 'login',
+      }
+    }
+
+    resource = {
+      samaccountname: 'Some41',
+      firstName:      'Some',
+    }
+
+    provided = process(
+      ldap_config: ldap_config,
+      resource:    resource,
+    )
+
+    expect(provided['lastname']).to be_nil
+  end
+end