diff --git a/beets/dbcore/types.py b/beets/dbcore/types.py
index 5aa2b9812..c85eb1a50 100644
--- a/beets/dbcore/types.py
+++ b/beets/dbcore/types.py
@@ -207,6 +207,12 @@ class String(Type):
     sql = u'TEXT'
     query = query.SubstringQuery
 
+    def normalize(self, value):
+        if value is None:
+            return self.null
+        else:
+            return self.model_type(value)
+
 
 class Boolean(Type):
     """A boolean type.
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 70fb5ad43..a31c6869b 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -271,6 +271,10 @@ Fixes:
   the current track in the queue.
   Thanks to :user:`aereaux`.
   :bug:`3722`
+* String-typed fields are now normalized to string values, avoiding an
+  occasional crash when using both the :doc:`/plugins/fetchart` and the
+  :doc:`/plugins/discogs` together.
+  :bug:`3773` :bug:`3774`
 * Fix a bug causing PIL to generate poor quality JPEGs when resizing artwork.
   :bug:`3743`
 
diff --git a/test/test_lyrics.py b/test/test_lyrics.py
index 833b86b3a..95b094e98 100644
--- a/test/test_lyrics.py
+++ b/test/test_lyrics.py
@@ -48,71 +48,72 @@ class LyricsPluginTest(unittest.TestCase):
         lyrics.LyricsPlugin()
 
     def test_search_artist(self):
-        item = Item(artist='Alice ft. Bob', title='song')
-        self.assertIn(('Alice ft. Bob', ['song']),
+        item = Item(artist=u'Alice ft. Bob', title=u'song')
+        self.assertIn((u'Alice ft. Bob', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertIn(('Alice', ['song']),
+        self.assertIn((u'Alice', [u'song']),
                       lyrics.search_pairs(item))
 
-        item = Item(artist='Alice feat Bob', title='song')
-        self.assertIn(('Alice feat Bob', ['song']),
+        item = Item(artist=u'Alice feat Bob', title=u'song')
+        self.assertIn((u'Alice feat Bob', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertIn(('Alice', ['song']),
+        self.assertIn((u'Alice', [u'song']),
                       lyrics.search_pairs(item))
 
-        item = Item(artist='Alice feat. Bob', title='song')
-        self.assertIn(('Alice feat. Bob', ['song']),
+        item = Item(artist=u'Alice feat. Bob', title=u'song')
+        self.assertIn((u'Alice feat. Bob', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertIn(('Alice', ['song']),
+        self.assertIn((u'Alice', [u'song']),
                       lyrics.search_pairs(item))
 
-        item = Item(artist='Alice feats Bob', title='song')
-        self.assertIn(('Alice feats Bob', ['song']),
+        item = Item(artist=u'Alice feats Bob', title=u'song')
+        self.assertIn((u'Alice feats Bob', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertNotIn(('Alice', ['song']),
+        self.assertNotIn((u'Alice', [u'song']),
                          lyrics.search_pairs(item))
 
-        item = Item(artist='Alice featuring Bob', title='song')
-        self.assertIn(('Alice featuring Bob', ['song']),
+        item = Item(artist=u'Alice featuring Bob', title=u'song')
+        self.assertIn((u'Alice featuring Bob', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertIn(('Alice', ['song']),
+        self.assertIn((u'Alice', [u'song']),
                       lyrics.search_pairs(item))
 
-        item = Item(artist='Alice & Bob', title='song')
-        self.assertIn(('Alice & Bob', ['song']),
+        item = Item(artist=u'Alice & Bob', title=u'song')
+        self.assertIn((u'Alice & Bob', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertIn(('Alice', ['song']),
+        self.assertIn((u'Alice', [u'song']),
                       lyrics.search_pairs(item))
 
-        item = Item(artist='Alice and Bob', title='song')
-        self.assertIn(('Alice and Bob', ['song']),
+        item = Item(artist=u'Alice and Bob', title=u'song')
+        self.assertIn((u'Alice and Bob', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertIn(('Alice', ['song']),
+        self.assertIn((u'Alice', [u'song']),
                       lyrics.search_pairs(item))
 
-        item = Item(artist='Alice and Bob', title='song')
-        self.assertEqual(('Alice and Bob', ['song']),
+        item = Item(artist=u'Alice and Bob', title=u'song')
+        self.assertEqual((u'Alice and Bob', [u'song']),
                          list(lyrics.search_pairs(item))[0])
 
     def test_search_artist_sort(self):
-        item = Item(artist='CHVRCHΞS', title='song', artist_sort='CHVRCHES')
-        self.assertIn(('CHVRCHΞS', ['song']),
+        item = Item(artist=u'CHVRCHΞS', title=u'song', artist_sort=u'CHVRCHES')
+        self.assertIn((u'CHVRCHΞS', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertIn(('CHVRCHES', ['song']),
+        self.assertIn((u'CHVRCHES', [u'song']),
                       lyrics.search_pairs(item))
 
         # Make sure that the original artist name is still the first entry
-        self.assertEqual(('CHVRCHΞS', ['song']),
+        self.assertEqual((u'CHVRCHΞS', [u'song']),
                          list(lyrics.search_pairs(item))[0])
 
-        item = Item(artist='横山克', title='song', artist_sort='Masaru Yokoyama')
-        self.assertIn(('横山克', ['song']),
+        item = Item(artist=u'横山克', title=u'song',
+                    artist_sort=u'Masaru Yokoyama')
+        self.assertIn((u'横山克', [u'song']),
                       lyrics.search_pairs(item))
-        self.assertIn(('Masaru Yokoyama', ['song']),
+        self.assertIn((u'Masaru Yokoyama', [u'song']),
                       lyrics.search_pairs(item))
 
         # Make sure that the original artist name is still the first entry
-        self.assertEqual(('横山克', ['song']),
+        self.assertEqual((u'横山克', [u'song']),
                          list(lyrics.search_pairs(item))[0])
 
     def test_search_pairs_multi_titles(self):