diff --git a/peer/main.tf b/peer/main.tf
index a31cead..7263175 100644
--- a/peer/main.tf
+++ b/peer/main.tf
@@ -159,7 +159,7 @@ module "nacl_rule_self" {
   rule_description  = local.self_label
   rule_definitions  = {}
   named_cidr_blocks = ["vpc"]
-  merge_cidr_blocks = { "vpc" = local.peer_cidr_block }
+  merge_cidr_blocks = { "vpc" = [local.peer_cidr_block] }
   rules             = ["all_inbound", "all_outbound"]
   rule_number       = var.rule_number
   rule_increment    = var.rule_increment
@@ -182,7 +182,7 @@ module "nacl_rule_peer" {
   rule_description  = local.peer_label
   rule_definitions  = {}
   named_cidr_blocks = ["vpc"]
-  merge_cidr_blocks = { "vpc" = local.self_cidr_block }
+  merge_cidr_blocks = { "vpc" = [local.self_cidr_block] }
   rules             = ["all_inbound", "all_outbound"]
   rule_number       = var.peer_rule_number
   rule_increment    = var.peer_rule_increment