diff --git a/vpc-interface-endpoint/outputs.tf b/vpc-interface-endpoint/outputs.tf
index 4db0d46..3d47cdd 100644
--- a/vpc-interface-endpoint/outputs.tf
+++ b/vpc-interface-endpoint/outputs.tf
@@ -7,6 +7,6 @@ output "vpce_service_info" {
     "dns_entry"             = aws_vpc_endpoint.interface_endpoint.dns_entry,
     "subnet_ids"            = aws_vpc_endpoint.interface_endpoint.subnet_ids,
     "network_interface_ids" = aws_vpc_endpoint.interface_endpoint.network_interface_ids,
-    "subnet_ip_map"         = zipmap(aws_vpc_endpoint.interface_endpoint.subnet_ids, aws_vpc_endpoint.interface_endpoint.network_interface_ids),
+    "subnet_ip_map"         = zipmap(tolist(aws_vpc_endpoint.interface_endpoint.subnet_ids), tolist(aws_vpc_endpoint.interface_endpoint.network_interface_ids)),
   }
 }