diff --git a/core/modules/locale/locale.install b/core/modules/locale/locale.install
index 11d1873..acf3a80 100644
--- a/core/modules/locale/locale.install
+++ b/core/modules/locale/locale.install
@@ -386,6 +386,7 @@ function locale_update_8005() {
   }
   $plural_lids = array_unique($plural_lids);
 
+  if (!empty($plural_lids)) {
   // Look up all translations for these source strings. Ordering by language
   // will group the strings by language, the 'plid' order will get the
   // strings in singular/plural order and 'plural' will get them in precise
@@ -468,6 +469,7 @@ function locale_update_8005() {
   db_delete('locales_target')
     ->condition('lid', $remove_lids, 'IN')
     ->execute();
+  }
 
   // Drop the primary key because it contains 'plural'.
   db_drop_primary_key('locales_target');
diff --git a/core/modules/simpletest/tests/upgrade/upgrade.language.test b/core/modules/simpletest/tests/upgrade/upgrade.language.test
index ecbbd12..ae7dd8f 100644
--- a/core/modules/simpletest/tests/upgrade/upgrade.language.test
+++ b/core/modules/simpletest/tests/upgrade/upgrade.language.test
@@ -136,4 +136,18 @@ class LanguageUpgradePathTestCase extends UpgradePathTestCase {
     $domains = locale_language_negotiation_url_domains();
     $this->assertTrue($domains['ca'] == $language_domain, t('Language domain for Catalan properly upgraded.'));
   }
+
+  /**
+   * Tests upgrading translations without plurals.
+   */
+  public function testLanguageNoPluralsUpgrade() {
+    // Remove all plural translations from the database.
+    db_delete('locales_target')->condition('plural', 0, '<>')->execute();
+
+    $this->assertTrue($this->performUpgrade(), t('The upgrade was completed successfully.'));
+
+    // Check if locale_update_8005 is succesfully completed by checking whether
+    // index 'plural' has been removed.
+    $this->assertFalse(db_index_exists('locales_target', 'plural'), t('Translations without plurals upgraded.'));
+  }
 }