diff --git a/core/modules/views/src/Plugin/views/PluginBase.php b/core/modules/views/src/Plugin/views/PluginBase.php
index e56dcae..420437c 100644
--- a/core/modules/views/src/Plugin/views/PluginBase.php
+++ b/core/modules/views/src/Plugin/views/PluginBase.php
@@ -365,6 +365,12 @@ protected function viewsTokenReplace($text, $tokens) {
       if (strpos($token, '{{') !== FALSE) {
         // Twig wants a token replacement array stripped of curly-brackets.
         $token = trim(str_replace(array('{', '}'), '', $token));
+
+        // We need to validate tokens are valid Twig variables. Twig uses the
+        // same variable naming rules as PHP.
+        // @see http://php.net/manual/en/language.variables.basics.php
+        assert('preg_match(\'/^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$/\', $token) === 1', 'Tokens need to be valid Twig variables.');
+
         $twig_tokens[$token] = $replacement;
       }
       else {
diff --git a/core/modules/views/src/Plugin/views/field/Field.php b/core/modules/views/src/Plugin/views/field/Field.php
index 98f1a59..e4e3b0a 100644
--- a/core/modules/views/src/Plugin/views/field/Field.php
+++ b/core/modules/views/src/Plugin/views/field/Field.php
@@ -913,7 +913,6 @@ protected function addSelfTokens(&$tokens, $item) {
       // Use \Drupal\Component\Utility\Xss::filterAdmin() because it's user data
       // and we can't be sure it is safe. We know nothing about the data,
       // though, so we can't really do much else.
-
       if (isset($item['raw'])) {
         $raw = $item['raw'];
 
diff --git a/core/modules/views/src/Plugin/views/field/FieldPluginBase.php b/core/modules/views/src/Plugin/views/field/FieldPluginBase.php
index f5bc20c..6107eb5 100644
--- a/core/modules/views/src/Plugin/views/field/FieldPluginBase.php
+++ b/core/modules/views/src/Plugin/views/field/FieldPluginBase.php
@@ -1676,7 +1676,8 @@ protected function getTokenValuesRecursive(array $array, array $parent_keys = ar
    * fields as a list. For example, the field that displays all terms
    * on a node might have tokens for the tid and the term.
    *
-   * By convention, tokens should follow the format of {{ token__subtoken }}
+   * By convention, tokens should follow the format of {{ token
+   * subtoken }}
    * where token is the field ID and subtoken is the field. If the
    * field ID is terms, then the tokens might be {{ terms__tid }} and
    * {{ terms__name }}.
diff --git a/core/modules/views/src/Tests/Plugin/PluginBaseTest.php b/core/modules/views/src/Tests/Plugin/PluginBaseTest.php
new file mode 100644
index 0000000..f4b5c2d
--- /dev/null
+++ b/core/modules/views/src/Tests/Plugin/PluginBaseTest.php
@@ -0,0 +1,61 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\views\Tests\Plugin\PluginBaseTest.
+ */
+
+namespace Drupal\views\Tests\Plugin;
+
+use Drupal\Core\Render\RenderContext;
+use Drupal\Core\Render\SafeString;
+use Drupal\simpletest\KernelTestBase;
+use Drupal\views\Plugin\views\PluginBase;
+
+/**
+ * Tests the PluginBase class.
+ *
+ * @group views
+ */
+class PluginBaseTest extends KernelTestBase {
+
+  /**
+   * @var TestPluginBase
+   */
+  var $testPluginBase;
+
+  public function setUp() {
+    parent::setUp();
+    $this->testPluginBase = new TestPluginBase();
+  }
+
+  /**
+   * Test that the token replacement in views works correctly.
+   */
+  public function testViewsTokenReplace() {
+    $text = '{{ langcode__value }} means {{ langcode }}';
+    $tokens = ['{{ langcode }}' => SafeString::create('English'), '{{ langcode__value }}' => 'en'];
+
+    $result = \Drupal::service('renderer')->executeInRenderContext(new RenderContext(), function () use ($text, $tokens) {
+      return $this->testPluginBase->viewsTokenReplace($text, $tokens);
+    });
+
+    $this->assertIdentical($result, 'en means English');
+  }
+
+}
+
+/**
+ * Helper class for using the PluginBase abstract class.
+ */
+class TestPluginBase extends PluginBase {
+
+  public function __construct() {
+    parent::__construct([], '', []);
+  }
+
+  public function viewsTokenReplace($text, $tokens) {
+    return parent::viewsTokenReplace($text, $tokens);
+  }
+
+}
diff --git a/core/modules/views/tests/modules/views_test_data/src/Plugin/views/field/FieldTest.php b/core/modules/views/tests/modules/views_test_data/src/Plugin/views/field/FieldTest.php
index 74d5d3d..0f8feef 100644
--- a/core/modules/views/tests/modules/views_test_data/src/Plugin/views/field/FieldTest.php
+++ b/core/modules/views/tests/modules/views_test_data/src/Plugin/views/field/FieldTest.php
@@ -46,7 +46,7 @@ public function getTestValue() {
    * Overrides Drupal\views\Plugin\views\field\FieldPluginBase::addSelfTokens().
    */
   protected function addSelfTokens(&$tokens, $item) {
-    $tokens['[test-token]'] = $this->getTestValue();
+    $tokens['[test__token]'] = $this->getTestValue();
   }
 
   /**