diff --git a/s3-bucket-sftp/main.tf b/s3-bucket-sftp/main.tf
index 2ca9667..453ef36 100644
--- a/s3-bucket-sftp/main.tf
+++ b/s3-bucket-sftp/main.tf
@@ -130,7 +130,7 @@ resource "aws_transfer_server" "sftp" {
   endpoint_details {
     vpc_id             = var.vpc_id
     subnet_ids         = var.subnet_ids
-    security_group_ids = module.security_group.security_group_id
+    security_group_ids = [module.security_group.security_group_id]
   }
   tags = {
     Deployment = "QMI"