diff --git a/core/modules/locale/locale.install b/core/modules/locale/locale.install
index 3f837f0f5d..225e952a7d 100644
--- a/core/modules/locale/locale.install
+++ b/core/modules/locale/locale.install
@@ -303,20 +303,3 @@ function locale_update_8300() {
   // the new key value collection.
   \Drupal::state()->delete('locale.translation_status');
 }
-
-/**
- * Fix old plural style.
- */
-function locale_update_8400() {
-  $batch = [
-    'operations' => [
-      ['_locale_fix_old_plural_style_batch_proccess', []]
-    ],
-    'finished' => '_locale_fix_old_plural_style_batch_finished',
-    'title' => t('Processing'),
-    'progress_message' => '',
-    'error_message' => t('The update has encountered an error.'),
-    'file' => drupal_get_path('module', 'locale') . '/locale.bulk.inc',
-  ];
-  batch_set($batch);
-}
diff --git a/core/modules/locale/locale.post_update.php b/core/modules/locale/locale.post_update.php
new file mode 100644
index 0000000000..122e9c1c75
--- /dev/null
+++ b/core/modules/locale/locale.post_update.php
@@ -0,0 +1,18 @@
+<?php
+
+/**
+ * Fix old plural style, like @count[2].
+ */
+function locale_post_update_fix_old_plural_style() {
+  $batch = [
+    'operations' => [
+      ['_locale_fix_old_plural_style_batch_proccess', []]
+    ],
+    'finished' => '_locale_fix_old_plural_style_batch_finished',
+    'title' => t('Processing'),
+    'progress_message' => '',
+    'error_message' => t('The update has encountered an error.'),
+    'file' => drupal_get_path('module', 'locale') . '/locale.bulk.inc',
+  ];
+  batch_set($batch);
+}
diff --git a/core/modules/locale/src/LocaleLookup.php b/core/modules/locale/src/LocaleLookup.php
index 9290efc305..213ba1e486 100644
--- a/core/modules/locale/src/LocaleLookup.php
+++ b/core/modules/locale/src/LocaleLookup.php
@@ -171,6 +171,10 @@ protected function resolveCacheMiss($offset) {
         }
       }
     }
+    else {
+      // Fix old style plural problem, when value contains @count[0-9].
+      $value = preg_replace('!@count\[\d+\]!', '@count', $value);
+    }
 
     $this->storage[$offset] = $value;
     // Disabling the usage of string caching allows a module to watch for
diff --git a/core/modules/locale/tests/src/Functional/LocaleLocaleLookupTest.php b/core/modules/locale/tests/src/Functional/LocaleLocaleLookupTest.php
index 5f3e5f7e80..3d2cca417e 100644
--- a/core/modules/locale/tests/src/Functional/LocaleLocaleLookupTest.php
+++ b/core/modules/locale/tests/src/Functional/LocaleLocaleLookupTest.php
@@ -4,6 +4,7 @@
 
 use Drupal\language\Entity\ConfigurableLanguage;
 use Drupal\Tests\BrowserTestBase;
+use Drupal\Tests\Core\Cache\CacheCollectorHelper;
 
 /**
  * Tests LocaleLookup.
@@ -55,4 +56,38 @@ public function testLanguageFallbackDefaults() {
     $this->assertEqual($context['operation'], 'locale_lookup');
   }
 
+  /**
+   * Test old plural style @count[number] fix.
+   */
+  public function testFixOldPluralStyle() {
+    /** @var \Drupal\locale\StringDatabaseStorage $string_storage */
+    $string_storage = \Drupal::service('locale.storage');
+
+    $string = $string_storage->findString(['source' => 'Member for', 'context' => '']);
+
+    // Create translation with old @count[2] plural style.
+    $string_storage->createTranslation([
+      'lid' => $string->getId(),
+      'language' => 'fr',
+      'translation' => '@count[2] old-plural-test',
+    ])->save();
+
+    // Assert that @count[2] was fixed with caching.
+    drupal_flush_all_caches();
+    $this->drupalGet('');
+    $this->assertSession()->pageTextContains('@count old-plural-test');
+
+    // Assert that @count[2] wasn't fixed after caching.
+    drupal_flush_all_caches();
+    $collector = new CacheCollectorHelper('locale:fr::authenticated', $this->container->get('cache.default'), $this->container->get('lock'));
+    $collector->set('Member for', '@count[2] old-plural back');
+    $collector->destruct();
+    $this->drupalGet('');
+    $this->assertSession()->pageTextContains('@count[2] old-plural back');
+
+    // Assert that source not changed.
+    $translation = $string_storage->findTranslation(['language' => 'fr', 'lid' => $string->getId()])->translation;
+    $this->assertSame('@count[2] old-plural-test', $translation);
+  }
+
 }