diff --git a/main.tf b/main.tf
index 71c1ae9..936c4a4 100644
--- a/main.tf
+++ b/main.tf
@@ -23,7 +23,7 @@ resource "aws_security_group_rule" "ingress_security_groups" {
   type                     = "ingress"
   from_port                = 0
   to_port                  = 0
-  protocol                 = "-1"
+  protocol                 = "tcp"
   source_security_group_id = "${element(var.security_groups, count.index)}"
   security_group_id        = "${join("", aws_security_group.default.*.id)}"
 }
@@ -34,7 +34,7 @@ resource "aws_security_group_rule" "ingress_cidr_blocks" {
   type              = "ingress"
   from_port         = 0
   to_port           = 0
-  protocol          = "-1"
+  protocol          = "tcp"
   cidr_blocks       = ["${var.allowed_cidr_blocks}"]
   security_group_id = "${join("", aws_security_group.default.*.id)}"
 }
@@ -45,7 +45,7 @@ resource "aws_security_group_rule" "egress" {
   type              = "egress"
   from_port         = 0
   to_port           = 0
-  protocol          = "-1"
+  protocol          = "tcp"
   cidr_blocks       = ["0.0.0.0/0"]
   security_group_id = "${join("", aws_security_group.default.*.id)}"
 }