diff --git a/installer/data/mysql/atomicupdate/bug_18050_aqbudget_constraint.perl b/installer/data/mysql/atomicupdate/bug_18050_aqbudget_constraint.perl
new file mode 100644
index 0000000000..f110bad237
--- /dev/null
+++ b/installer/data/mysql/atomicupdate/bug_18050_aqbudget_constraint.perl
@@ -0,0 +1,20 @@
+$DBversion = 'XXX'; # will be replaced by the RM
+if( CheckVersion( $DBversion ) ) {
+    my $count_missing_budget = $dbh->selectrow_arrayref(q|
+        SELECT COUNT(*) FROM aqbudgets ab WHERE NOT EXISTS
+            (SELECT * FROM aqbudgetperiods abp WHERE abp.budget_period_id = ab.budget_period_id)
+
+    |);
+
+    if ( !foreign_key_exists( 'aqbudgets', 'aqbudgetperiods_ibfk_1' ) && $count_missing_budget->[0] == 0 ) {
+        $dbh->do(q|
+            ALTER TABLE aqbudgets ADD CONSTRAINT `aqbudgetperiods_ibfk_1` FOREIGN KEY (`budget_period_id`) REFERENCES `aqbudgetperiods` (`budget_period_id`) ON UPDATE CASCADE ON DELETE CASCADE
+        |);
+        NewVersion( $DBversion, 18050, "Add FK constraint on aqbudgets.budget_period_id");
+    } elsif ( $count_missing_budget->[0] > 0 )  {
+        NewVersion( $DBversion, 18050, "FK constraint on aqbudgets.budget_period_id couldn't be added. There are $count_missing_budget->[0] funds in your database that are not linked to a valid budget.");
+    } else {
+        NewVersion( $DBversion, 18050, "FK constraint on aqbudgets.budget already exists");
+    }
+
+}
diff --git a/installer/data/mysql/kohastructure.sql b/installer/data/mysql/kohastructure.sql
index 6e092eae80..b46380a598 100644
--- a/installer/data/mysql/kohastructure.sql
+++ b/installer/data/mysql/kohastructure.sql
@@ -2858,7 +2858,8 @@ CREATE TABLE `aqbudgets` ( -- information related to Funds
   KEY `budget_code` (`budget_code`),
   KEY `budget_branchcode` (`budget_branchcode`),
   KEY `budget_period_id` (`budget_period_id`),
-  KEY `budget_owner_id` (`budget_owner_id`)
+  KEY `budget_owner_id` (`budget_owner_id`),
+  CONSTRAINT `aqbudgetperiods_ibfk_1` FOREIGN KEY (`budget_period_id`) REFERENCES `aqbudgetperiods` (`budget_period_id`) ON UPDATE CASCADE ON DELETE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
 
 --