diff --git a/lib/internal/Magento/Framework/View/Layout/etc/elements.xsd b/lib/internal/Magento/Framework/View/Layout/etc/elements.xsd
index fd674063efca7..2cb8b79dfbbc0 100644
--- a/lib/internal/Magento/Framework/View/Layout/etc/elements.xsd
+++ b/lib/internal/Magento/Framework/View/Layout/etc/elements.xsd
@@ -119,7 +119,7 @@
 
     <xs:simpleType name="htmlClassType">
         <xs:restriction base="xs:string">
-            <xs:pattern value="[a-zA-Z\d\-_/:.\[\]&amp;@() ]*"/>
+            <xs:pattern value="[a-zA-Z\d\-_/:.\[\]&amp;@()!% ]*"/>
         </xs:restriction>
     </xs:simpleType>