diff --git a/core/lib/Drupal/Core/Config/Entity/EntityBundleWithPluralLabelsTrait.php b/core/lib/Drupal/Core/Config/Entity/EntityBundleWithPluralLabelsTrait.php
index e5077dcf46..c8e4133ae2 100644
--- a/core/lib/Drupal/Core/Config/Entity/EntityBundleWithPluralLabelsTrait.php
+++ b/core/lib/Drupal/Core/Config/Entity/EntityBundleWithPluralLabelsTrait.php
@@ -67,7 +67,11 @@ public function getPluralLabel() {
    * {@inheritdoc}
    */
   public function getCountLabel($count) {
-    $index = static::getPluralIndex($count);
+    if (($index = static::getPluralIndex($count)) === -1) {
+      // If the index cannot be computed, fallback to a single plural variant.
+      $index = $count > 1 ? 1 : 0;
+    }
+
     $label_count = empty($this->label_count) ? [] : explode(PluralTranslatableMarkup::DELIMITER, $this->label_count);
     if (isset($label_count[$index])) {
       return new FormattableMarkup($label_count[$index], ['@count' => $count]);