diff --git a/solutions/fully-configurable/variables.tf b/solutions/fully-configurable/variables.tf
index c261c807..feb345d1 100644
--- a/solutions/fully-configurable/variables.tf
+++ b/solutions/fully-configurable/variables.tf
@@ -33,11 +33,9 @@ variable "prefix" {
       ])
     )
     error_message = "Prefix must begin with a lowercase letter and may contain only lowercase letters, digits, and hyphens '-'. It must not end with a hyphen('-'), and cannot contain consecutive hyphens ('--')."
-  }
-
-  validation {
+  }  validation {
     # must not exceed 16 characters in length
-    condition     = length(var.prefix) <= 16
+    condition = var.prefix == null || var.prefix == "" ? true : length(var.prefix) <= 16
     error_message = "Prefix must not exceed 16 characters."
   }
 }
diff --git a/solutions/security-enforced/variables.tf b/solutions/security-enforced/variables.tf
index eb9a5a72..f945cc2a 100644
--- a/solutions/security-enforced/variables.tf
+++ b/solutions/security-enforced/variables.tf
@@ -33,11 +33,9 @@ variable "prefix" {
       ])
     )
     error_message = "Prefix must begin with a lowercase letter and may contain only lowercase letters, digits, and hyphens '-'. It must not end with a hyphen('-'), and cannot contain consecutive hyphens ('--')."
-  }
-
-  validation {
+  }  validation {
     # must not exceed 16 characters in length
-    condition     = length(var.prefix) <= 16
+    condition = var.prefix == null || var.prefix == "" ? true : length(var.prefix) <= 16
     error_message = "Prefix must not exceed 16 characters."
   }
 }