diff --git a/core/lib/Drupal/Component/Gettext/PoItem.php b/core/lib/Drupal/Component/Gettext/PoItem.php
index c845c4b..f673752 100644
--- a/core/lib/Drupal/Component/Gettext/PoItem.php
+++ b/core/lib/Drupal/Component/Gettext/PoItem.php
@@ -193,7 +193,7 @@ public function setFromArray(array $values = array()) {
         strpos($this->_source, LOCALE_PLURAL_DELIMITER) !== FALSE) {
       $this->setSource(explode(LOCALE_PLURAL_DELIMITER, $this->_source));
       $this->setTranslation(explode(LOCALE_PLURAL_DELIMITER, $this->_translation));
-      $this->setPlural(count($this->_translation) > 1);
+      $this->setPlural(count($this->_source) > 1);
     }
   }