diff --git a/src/Validate/Common/BaseCurrency.php b/src/Validate/Common/BaseCurrency.php
index f9f1ccc..a5e4c46 100644
--- a/src/Validate/Common/BaseCurrency.php
+++ b/src/Validate/Common/BaseCurrency.php
@@ -45,7 +45,8 @@ private function validateNode(NodeInterface $node, Asserts $asserts, string $loc
     {
         $currencyExists = $node->attributes()->exists('Moneda');
         $currency = $node['Moneda'];
-        $currencyExplanation = $currencyExists ? $currency ?: '(vacía)' : '(ninguna)';
+        $currencyExplanation = $currencyExists ? ($currency ?: '(vacía)') : '(ninguna)';
+
         $asserts->put(
             $this->getAssertCode(sprintf('-%03d', $count)),
             'La moneda solo se especifica en caso de que sea diferente a moneda nacional',
diff --git a/src/Validate/Common/BaseExchangeRate.php b/src/Validate/Common/BaseExchangeRate.php
index 7a07531..bd64a63 100644
--- a/src/Validate/Common/BaseExchangeRate.php
+++ b/src/Validate/Common/BaseExchangeRate.php
@@ -45,7 +45,7 @@ private function validateNode(NodeInterface $node, Asserts $asserts, string $loc
     {
         $currencyExists = $node->attributes()->exists('Moneda');
         $currency = $node['Moneda'];
-        $currencyExplanation = $currencyExists ? $currency ?: '(vacía)' : '(ninguna)';
+        $currencyExplanation = $currencyExists ? ($currency ?: '(vacía)') : '(ninguna)';
 
         $exchangeRate = $node['TipCamb'];
         $asserts->put(