diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index 76c5841180..c6aa2e646f 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -985,11 +985,19 @@ class DB(object):
         else:
             if callable(getattr(data, 'read', None)):
                 data = data.read()
-            try:
-                save_cover_data_to(data, path)
-            except (IOError, OSError):
-                time.sleep(0.2)
-                save_cover_data_to(data, path)
+            if data is None:
+                if os.path.exists(path):
+                    try:
+                        os.remove(path)
+                    except (IOError, OSError):
+                        time.sleep(0.2)
+                        os.remove(path)
+            else:
+                try:
+                    save_cover_data_to(data, path)
+                except (IOError, OSError):
+                    time.sleep(0.2)
+                    save_cover_data_to(data, path)
 
     def copy_format_to(self, book_id, fmt, fname, path, dest,
                        windows_atomic_move=None, use_hardlink=False):
diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index ba68de23a7..b79ff2a31b 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -826,7 +826,8 @@ class Cache(object):
     @write_api
     def set_cover(self, book_id_data_map):
         ''' Set the cover for this book.  data can be either a QImage,
-        QPixmap, file object or bytestring '''
+        QPixmap, file object or bytestring. It can also be None, in which
+        case any existing cover is removed. '''
 
         for book_id, data in book_id_data_map.iteritems():
             try:
@@ -836,7 +837,8 @@ class Cache(object):
                 path = self._field_for('path', book_id).replace('/', os.sep)
 
             self.backend.set_cover(book_id, path, data)
-        self._set_field('cover', {book_id:1 for book_id in book_id_data_map})
+        return self._set_field('cover', {
+            book_id:(0 if data is None else 1) for book_id, data in book_id_data_map.iteritems()})
 
     @write_api
     def set_metadata(self, book_id, mi, ignore_errors=False, force_changes=False,
diff --git a/src/calibre/db/tests/writing.py b/src/calibre/db/tests/writing.py
index 9ec368dd83..5e25155713 100644
--- a/src/calibre/db/tests/writing.py
+++ b/src/calibre/db/tests/writing.py
@@ -355,7 +355,24 @@ class WritingTest(BaseTest):
             ae(opf.authors, ['author1', 'author2'])
     # }}}
 
-    def test_set_cover(self):
+    def test_set_cover(self):  # {{{
         ' Test setting of cover '
-        self.assertTrue(False, 'TODO: test set_cover() and set_metadata()')
+        cache = self.init_cache()
+        ae = self.assertEqual
+
+        # Test removing a cover
+        ae(cache.field_for('cover', 1), 1)
+        ae(cache.set_cover({1:None}), set([1]))
+        ae(cache.field_for('cover', 1), 0)
+
+        img = b'\xff\xd8\xff\xe0\x00\x10JFIF\x00\x01\x01\x01\x00`\x00`\x00\x00\xff\xe1\x00\x16Exif\x00\x00II*\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xdb\x00C\x00\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\xff\xdb\x00C\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01\xff\xc0\x00\x11\x08\x00\x01\x00\x01\x03\x01"\x00\x02\x11\x01\x03\x11\x01\xff\xc4\x00\x15\x00\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\n\xff\xc4\x00\x14\x10\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xc4\x00\x14\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xc4\x00\x14\x11\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xda\x00\x0c\x03\x01\x00\x02\x11\x03\x11\x00?\x00\xbf\x80\x01\xff\xd9'  # noqa {{{ }}}
+        # Test setting a cover
+        ae(cache.set_cover({bid:img for bid in (1, 2, 3)}), {1, 2, 3})
+        for book_id in (1, 2, 3):
+            ae(cache.cover(book_id), img, 'Cover was not set correctly for book %d' % book_id)
+    # }}}
+
+    def test_set_metadata(self):
+        ' Test setting of metadata '
+        self.assertTrue(False, 'TODO: test set_metadata()')
 
diff --git a/src/calibre/db/write.py b/src/calibre/db/write.py
index 1bdbabf082..7fdb2070c0 100644
--- a/src/calibre/db/write.py
+++ b/src/calibre/db/write.py
@@ -461,7 +461,7 @@ class Writer(object):
         dt = field.metadata['datatype']
         self.accept_vals = lambda x: True
         if dt == 'composite' or field.name in {
-            'id', 'cover', 'size', 'path', 'formats', 'news'}:
+            'id', 'size', 'path', 'formats', 'news'}:
             self.set_books_func = dummy
         elif self.name[0] == '#' and self.name.endswith('_index'):
             self.set_books_func = custom_series_index