diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index 305d1581d7..bd89e12044 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -2356,7 +2356,7 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
         rating = int(rating)
         self.conn.execute('DELETE FROM books_ratings_link WHERE book=?',(id,))
         rat = self.conn.get('SELECT id FROM ratings WHERE rating=?', (rating,), all=False)
-        rat = rat if rat else self.conn.execute('INSERT INTO ratings(rating) VALUES (?)', (rating,)).lastrowid
+        rat = rat if rat is not None else self.conn.execute('INSERT INTO ratings(rating) VALUES (?)', (rating,)).lastrowid
         self.conn.execute('INSERT INTO books_ratings_link(book, rating) VALUES (?,?)', (id, rat))
         self.dirtied([id], commit=False)
         if commit: