diff --git a/src/app/SignupCode.php b/src/app/SignupCode.php
index 73ecd7af..0e5e1559 100644
--- a/src/app/SignupCode.php
+++ b/src/app/SignupCode.php
@@ -1,106 +1,106 @@
 <?php
 
 namespace App;
 
 use Carbon\Carbon;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\SoftDeletes;
 
 /**
  * The eloquent definition of a SignupCode.
  *
  * @property string         $code        The full code identifier
  * @property \Carbon\Carbon $created_at  The creation timestamp
  * @property \Carbon\Carbon $deleted_at  The deletion timestamp
- * @property string         $domain_part Email domain
- * @property string         $email       Email address
+ * @property ?string        $domain_part Email domain
+ * @property ?string        $email       Email address
  * @property \Carbon\Carbon $expires_at  The code expiration timestamp
- * @property string         $first_name  Firstname
+ * @property ?string        $first_name  Firstname
  * @property string         $ip_address  IP address the request came from
- * @property string         $last_name   Lastname
- * @property string         $local_part  Email local part
- * @property string         $plan        Plan title
+ * @property ?string        $last_name   Lastname
+ * @property ?string        $local_part  Email local part
+ * @property ?string        $plan        Plan title
  * @property string         $short_code  Short validation code
  * @property \Carbon\Carbon $updated_at  The update timestamp
- * @property string         $voucher     Voucher discount code
+ * @property ?string        $voucher     Voucher discount code
  */
 class SignupCode extends Model
 {
     use SoftDeletes;
 
     public const SHORTCODE_LENGTH  = 5;
     public const CODE_LENGTH       = 32;
 
     // Code expires after so many hours
     public const CODE_EXP_HOURS    = 24;
 
 
     /**
      * The primary key associated with the table.
      *
      * @var string
      */
     protected $primaryKey = 'code';
 
     /**
      * Indicates if the IDs are auto-incrementing.
      *
      * @var bool
      */
     public $incrementing = false;
 
     /**
      * The "type" of the auto-incrementing ID.
      *
      * @var string
      */
     protected $keyType = 'string';
 
     /**
      * The attributes that are mass assignable.
      *
      * @var array
      */
     protected $fillable = [
         'code',
         'email',
         'expires_at',
         'first_name',
         'last_name',
         'plan',
         'short_code',
         'voucher'
     ];
 
     protected $casts = ['headers' => 'array'];
 
     /**
      * The attributes that should be mutated to dates.
      *
      * @var array
      */
     protected $dates = ['expires_at'];
 
     /**
      * Check if code is expired.
      *
      * @return bool True if code is expired, False otherwise
      */
     public function isExpired()
     {
         // @phpstan-ignore-next-line
         return $this->expires_at ? Carbon::now()->gte($this->expires_at) : false;
     }
 
     /**
      * Generate a short code (for human).
      *
      * @return string
      */
     public static function generateShortCode(): string
     {
         $code_length = env('SIGNUP_CODE_LENGTH', self::SHORTCODE_LENGTH);
 
         return \App\Utils::randStr($code_length);
     }
 }