diff --git a/README.md b/README.md
index be8ff0f..1e62621 100644
--- a/README.md
+++ b/README.md
@@ -1754,7 +1754,7 @@ list(object({
     expiration = optional(list(object({
       days                         = optional(number)
       date                         = optional(string)
-      expired_object_delete_marker = optional(bool, true)
+      expired_object_delete_marker = optional(bool)
     })), [])
     transition = optional(list(object({
       days          = optional(number)
diff --git a/variables.tf b/variables.tf
index 930a7e3..d084f7f 100644
--- a/variables.tf
+++ b/variables.tf
@@ -1144,7 +1144,7 @@ variable "s3_lifecycle_rules" {
     expiration = optional(list(object({
       days                         = optional(number)
       date                         = optional(string)
-      expired_object_delete_marker = optional(bool, true)
+      expired_object_delete_marker = optional(bool)
     })), [])
     transition = optional(list(object({
       days          = optional(number)