diff --git a/schema/ttrss_schema_mysql.sql b/schema/ttrss_schema_mysql.sql
index a3a7b695..61fcff45 100644
--- a/schema/ttrss_schema_mysql.sql
+++ b/schema/ttrss_schema_mysql.sql
@@ -432,7 +432,7 @@ create table ttrss_linked_instances (id integer not null primary key auto_increm
 	last_connected datetime not null,
 	last_status_in integer not null,
 	last_status_out integer not null,
-	access_key varchar(250) not null,
+	access_key varchar(250) not null unique,
 	access_url text not null) TYPE=InnoDB DEFAULT CHARSET=UTF8;
 
 create table ttrss_linked_feeds (
diff --git a/schema/ttrss_schema_pgsql.sql b/schema/ttrss_schema_pgsql.sql
index 1e60d3a1..67fe8a8d 100644
--- a/schema/ttrss_schema_pgsql.sql
+++ b/schema/ttrss_schema_pgsql.sql
@@ -392,7 +392,7 @@ create table ttrss_linked_instances (id serial not null primary key,
 	last_connected timestamp not null,
 	last_status_in integer not null,
 	last_status_out integer not null,
-	access_key varchar(250) not null,
+	access_key varchar(250) not null unique,
 	access_url text not null);
 
 create table ttrss_linked_feeds (
diff --git a/schema/versions/mysql/84.sql b/schema/versions/mysql/84.sql
index 3255d6f5..5fe530c9 100644
--- a/schema/versions/mysql/84.sql
+++ b/schema/versions/mysql/84.sql
@@ -4,7 +4,7 @@ create table ttrss_linked_instances (id integer not null primary key auto_increm
 	last_connected timestamp not null,
 	last_status_in integer not null,
 	last_status_out integer not null,
-	access_key varchar(250) not null,
+	access_key varchar(250) not null unique,
 	access_url text not null) TYPE=InnoDB DEFAULT CHARSET=UTF8;
 
 create table ttrss_linked_feeds (
diff --git a/schema/versions/pgsql/84.sql b/schema/versions/pgsql/84.sql
index 85b9cf20..55a7caf7 100644
--- a/schema/versions/pgsql/84.sql
+++ b/schema/versions/pgsql/84.sql
@@ -4,7 +4,7 @@ create table ttrss_linked_instances (id serial not null primary key,
 	last_connected timestamp not null,
 	last_status_in integer not null,
 	last_status_out integer not null,
-	access_key varchar(250) not null,
+	access_key varchar(250) not null unique,
 	access_url text not null);
 
 create table ttrss_linked_feeds (