diff --git a/core/modules/node/templates/node.html.twig b/core/modules/node/templates/node.html.twig
index ede27e6..feead8a 100644
--- a/core/modules/node/templates/node.html.twig
+++ b/core/modules/node/templates/node.html.twig
@@ -81,11 +81,11 @@
 {%
   set add_classes = [
     'node',
-    'node--type-' ~ node.bundle,
+    'node--type-' ~ node.bundle|clean_class,
     node.promoted ? 'node--promoted',
     node.sticky ? 'node--sticky',
     not node.published ? 'node--unpublished',
-    'node--view-mode-' ~ view_mode,
+    'node--view-mode-' ~ view_mode|clean_class,
     preview ? ' node--preview'
   ]
 %}
diff --git a/core/themes/bartik/templates/node.html.twig b/core/themes/bartik/templates/node.html.twig
index 43f4d88..29a9e9f 100644
--- a/core/themes/bartik/templates/node.html.twig
+++ b/core/themes/bartik/templates/node.html.twig
@@ -74,11 +74,11 @@
 {%
   set add_classes = [
     'node',
-    'node--type-' ~ node.bundle,
+    'node--type-' ~ node.bundle|clean_class,
     node.promoted ? 'node--promoted',
     node.sticky ? 'node--sticky',
     not node.published ? 'node--unpublished',
-    'node--view-mode-' ~ view_mode,
+    'node--view-mode-' ~ view_mode|clean_class,
     preview ? ' node--preview',
     'clearfix'
   ]