diff --git a/tf/modules/ecs_cluster/main.tf b/tf/modules/ecs_cluster/main.tf
index aa20e24d..805ae90f 100644
--- a/tf/modules/ecs_cluster/main.tf
+++ b/tf/modules/ecs_cluster/main.tf
@@ -72,7 +72,7 @@ resource "aws_security_group" "web" {
     cidr_blocks = [
       "0.0.0.0/0",
     ]
-    ipv6_cidr_blocks = ["0::0/0"]
+    ipv6_cidr_blocks = ["::/0"]
   }
 
   tags = var.tags
@@ -121,7 +121,7 @@ resource "aws_security_group" "container_host" {
     to_port          = 0
     protocol         = "-1"
     cidr_blocks      = ["0.0.0.0/0"]
-    ipv6_cidr_blocks = ["0::0/0"]
+    ipv6_cidr_blocks = ["::/0"]
   }
 
   tags = var.tags