diff --git a/dlibrary/dlibrary.py b/dlibrary/dlibrary.py
index 3d313b5..635157c 100755
--- a/dlibrary/dlibrary.py
+++ b/dlibrary/dlibrary.py
@@ -101,8 +101,8 @@ async def fetch_async(args):
     cur = con.cursor()
 
     cur.execute("CREATE TABLE IF NOT EXISTS works(id TEXT PRIMARY KEY, title TEXT, circle TEXT, date TEXT, description TEXT, series TEXT, virtual INT)")
-    cur.execute("CREATE TABLE IF NOT EXISTS authors(author TEXT, work TEXT, FOREIGN KEY(work) REFERENCES works(id))")
-    cur.execute("CREATE TABLE IF NOT EXISTS tags(tag TEXT, work TEXT, FOREIGN KEY(work) REFERENCES works(id))")
+    cur.execute("CREATE TABLE IF NOT EXISTS authors(author TEXT, work TEXT, FOREIGN KEY(work) REFERENCES works(id), PRIMARY KEY(author, work))")
+    cur.execute("CREATE TABLE IF NOT EXISTS tags(tag TEXT, work TEXT, FOREIGN KEY(work) REFERENCES works(id), PRIMARY KEY(tag, work))")
 
     thumbnails_dir = args.destdir / 'site' / 'thumbnails'
     thumbnails_dir.mkdir(parents=True, exist_ok=True)