diff --git a/aws/elasticache/variables.tf b/aws/elasticache/variables.tf
index d0c34f1f..724d22f2 100644
--- a/aws/elasticache/variables.tf
+++ b/aws/elasticache/variables.tf
@@ -87,7 +87,7 @@ variable "transit_encryption_mode" {
   description = "when migrating from no encryption to encryption, this must be set to 'preferred', then apply changes, then set to 'required'"
 
   validation {
-    condition     = contains(["required", "preferred"], var.transit_encryption_mode)
+    condition     = contains(["required", "preferred", null], var.transit_encryption_mode)
     error_message = "transit_encryption_mode must be either 'required' or 'preferred'"
   }
 }
diff --git a/aws/stack/app/variables.tf b/aws/stack/app/variables.tf
index 18f3c53e..9e7c33a7 100644
--- a/aws/stack/app/variables.tf
+++ b/aws/stack/app/variables.tf
@@ -403,7 +403,7 @@ variable "elasticache_transit_encryption_mode" {
   description = "when migrating from no encryption to encryption, this must be set to 'preferred', then apply changes, then set to 'required'"
 
   validation {
-    condition     = contains(["required", "preferred"], var.elasticache_transit_encryption_mode)
+    condition     = contains(["required", "preferred", null], var.elasticache_transit_encryption_mode)
     error_message = "elasticache_transit_encryption_mode must be either 'required' or 'preferred'"
   }
 }