diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index 2dc5d557f7..7ed653093c 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -1057,7 +1057,7 @@ class Cache(object):
 
     @write_api
     def set_metadata(self, book_id, mi, ignore_errors=False, force_changes=False,
-                     set_title=True, set_authors=True):
+                     set_title=True, set_authors=True, allow_case_change=False):
         '''
         Set metadata for the book `id` from the `Metadata` object `mi`
 
@@ -1078,13 +1078,13 @@ class Cache(object):
         except (AttributeError, TypeError):
             pass
 
-        def set_field(name, val, **kwargs):
-            self._set_field(name, {book_id:val}, **kwargs)
+        def set_field(name, val):
+            self._set_field(name, {book_id:val}, do_path_update=False, allow_case_change=allow_case_change)
 
         path_changed = False
         if set_title and mi.title:
             path_changed = True
-            set_field('title', mi.title, do_path_update=False)
+            set_field('title', mi.title)
         if set_authors:
             path_changed = True
             if not mi.authors:
@@ -1092,7 +1092,7 @@ class Cache(object):
             authors = []
             for a in mi.authors:
                 authors += string_to_authors(a)
-            set_field('authors', authors, do_path_update=False)
+            set_field('authors', authors)
 
         if path_changed:
             self._update_path({book_id})
diff --git a/src/calibre/db/tests/writing.py b/src/calibre/db/tests/writing.py
index 19f6e70f48..f4b8553164 100644
--- a/src/calibre/db/tests/writing.py
+++ b/src/calibre/db/tests/writing.py
@@ -420,6 +420,13 @@ class WritingTest(BaseTest):
         ae(nmi2.get_extra('#series'), 1.0)
         self.compare_metadata(nmi2, oldmi2, exclude={'last_modified', 'format_metadata', '#series_index'})
 
+        cache = self.init_cache(self.cloned_library)
+        mi = cache.get_metadata(1)
+        otags = mi.tags
+        mi.tags = [x.upper() for x in mi.tags]
+        cache.set_metadata(3, mi)
+        self.assertEqual(set(otags), set(cache.field_for('tags', 3)), 'case changes should not be allowed in set_metadata')
+
     # }}}
 
     def test_conversion_options(self):  # {{{
@@ -574,4 +581,3 @@ class WritingTest(BaseTest):
         cache.add_format(1, 'ADD', BytesIO(b'xxxx'))
         test_invalidate()
     # }}}
-