diff --git a/init-db.sql b/init-db.sql
index ebbeb9b..3c1c960 100644
--- a/init-db.sql
+++ b/init-db.sql
@@ -1,6 +1,6 @@
 CREATE TABLE IF NOT EXISTS files (
     id serial,
-    file_id varchar(255) not null,
+    file_id varchar(255) not null unique,
     file_name varchar(255) not null,
     valid_till timestamp not null,
     kind varchar(255) not null,