diff --git a/whipper/common/mbngs.py b/whipper/common/mbngs.py
index 252e18cf..3157c4b5 100644
--- a/whipper/common/mbngs.py
+++ b/whipper/common/mbngs.py
@@ -153,88 +153,78 @@ def getIds(self):
 
 
 def _getWorks(recording):
-    """Get "performance of" works out of a recording."""
+    """
+    Get 'performance of' works out of a recording.
+
+   :param recording: recording entity in MusicBrainz
+   :type recording: dict
+   :returns: list of works being a performance of a recording
+   :rtype: list
+    """
     works = []
-    valid_work_rel_types = [
-        'a3005666-a872-32c3-ad06-98af558e99b0',  # "Performance"
-    ]
+    valid_type_id = 'a3005666-a872-32c3-ad06-98af558e99b0'  # "Performance"
     if 'work-relation-list' in recording:
         for work in recording['work-relation-list']:
-            if work['type-id'] in valid_work_rel_types:
+            if work['type-id'] == valid_type_id:
                 works.append(work['work'])
     return works
 
 
 def _getWorksId(works):
-    """Get work ids from "performance of" works"""
-    ids = set()  # using a set to prevent duplicates
+    """
+    Get work IDs from 'performance of' works.
+
+    :param works: list of works being a performance of a recording
+    :type works: list
+    :returns: sorted list of work IDs (without duplicates)
+    :rtype: list
+    """
+    ids = set()
     for work in works:
         ids.add(work['id'])
-    # convert back to list since mutagen doesn't support set
-    return list(ids)
+    return sorted(ids)  # convert to list: mutagen doesn't support set
 
 
 def _getComposers(works):
     """
-    Extract composer(s) from works' artist-relation-list into a list
+    Get composer(s) from works' artist-relation-list.
 
+    :param works: list of works being a performance of a recording
+    :type works: list
+    :returns: sorted list of composers (without duplicates)
     :rtype: list
     """
-    composers = set()  # using a set to prevent duplicates
-    valid_artist_rel_type = [
-        'd59d99ea-23d4-4a80-b066-edca32ee158f',  # "Composer"
-    ]
+    composers = set()
+    valid_type_id = 'd59d99ea-23d4-4a80-b066-edca32ee158f'  # "Composer"
     for work in works:
         if 'artist-relation-list' in work:
             for artist_relation in work['artist-relation-list']:
-                if artist_relation['type-id'] in valid_artist_rel_type:
+                if artist_relation['type-id'] == valid_type_id:
                     composerName = artist_relation['artist']['name']
                     composers.add(composerName)
-    # convert back to list since mutagen doesn't support set
-    return list(composers)
+    return sorted(composers)  # convert to list: mutagen doesn't support set
 
 
 def _getPerformers(recording):
     """
-    Extract performer(s) from recordings' artist-relation-list
+    Get performer(s) from recordings' artist-relation-list.
 
+    :param recording: recording entity in MusicBrainz
+    :type recording: dict
+    :returns: sorted list of performers' names (without duplicates)
     :rtype: list
     """
-    performers = []
-    valid_type_id = [
+    performers = set()
+    valid_type_id = {
         '59054b12-01ac-43ee-a618-285fd397e461',  # "Instruments"
         '0fdbe3c6-7700-4a31-ae54-b53f06ae1cfa',  # "Vocals"
         '628a9658-f54c-4142-b0c0-95f031b544da'   # "Performers"
-    ]
-    common_attribute_name = [
-        'guest', 'additional', 'solo'
-    ]
+    }
     if 'artist-relation-list' in recording:
         for artist_relation in recording['artist-relation-list']:
             if artist_relation['type-id'] in valid_type_id:
-                type = artist_relation['type']
-                name = artist_relation['artist']['name']
-
-                if 'attribute-list' in artist_relation:
-                    prefix = ''  # additional guest solo
-                    others = []  # types of vocal, instruments
-                    for attribute in artist_relation['attribute-list']:
-                        if attribute in common_attribute_name:
-                            # this works since attributes' order is
-                            # alphabetical which will correctly match the given
-                            # standard order
-                            # see: https://musicbrainz.org/relationship/eb10f8a0-0f4c-4dce-aa47-87bcb2bc42f3  # noqa E501
-                            prefix += attribute + ' '
-                        else:
-                            others.append(attribute)
-                    # if "guest performer: artist", `suffix` is `type` by
-                    # default else "guest solo piano, organ : artist"
-                    suffix = type if len(others) == 0 else ', '.join(others)
-                    type = prefix + suffix
-
-                performer = "%s: %s" % (type, name)
-                performers.append(performer)
-    return performers
+                performers.add(artist_relation['artist']['name'])
+    return sorted(performers)  # convert to list: mutagen doesn't support set
 
 
 def _getMetadata(release, discid=None, country=None):
diff --git a/whipper/test/test_common_mbngs.py b/whipper/test/test_common_mbngs.py
index 6e967854..eae65684 100644
--- a/whipper/test/test_common_mbngs.py
+++ b/whipper/test/test_common_mbngs.py
@@ -46,8 +46,9 @@ def testTrackTitle(self):
 
     def testComposersAndPerformers(self):
         """
-        Test if composers and performers are extracted properly
-        see https://github.com/whipper-team/whipper/issues/191
+        Test whether composers and performers are extracted properly.
+
+        See: https://github.com/whipper-team/whipper/issues/191
         """
         # Using: Mama Said - Lenny Kravitz
         # https://musicbrainz.org/release/410f99f8-a876-3416-bd8e-42233a00a477
@@ -60,12 +61,8 @@ def testComposersAndPerformers(self):
                                       discid='bIOeHwHT0aZJiENIYjAmoNxCPuA-')
         track1 = metadata.tracks[0]
         self.assertEqual(track1.composers,
-                         list({'Hal Fredericks', 'Michael Kamen'}))
-        self.assertEqual(track1.performers, ['bass guitar, guitar family, '
-                                             'mellotron, membranophone: Lenny '
-                                             'Kravitz',
-                                             'guest guitar: Slash',
-                                             'vocal: Lenny Kravitz'])
+                         ['Hal Fredericks', 'Michael Kamen'])
+        self.assertEqual(track1.performers, ['Lenny Kravitz', 'Slash'])
 
     def test2MeterSessies10(self):
         # various artists, multiple artists per track