diff --git a/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp b/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
index b8c05f5e625..e30fdc30f1f 100644
--- a/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
+++ b/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
@@ -99,7 +99,23 @@ void XMLDocumentBuilder::element_start(const XML::Name& name, HashMap<XML::Name,
         m_namespace_stack.last().depth += 1;
     }
 
-    auto node = DOM::create_element(m_document, MUST(FlyString::from_deprecated_fly_string(name)), m_namespace).release_value_but_fixme_should_propagate_errors();
+    auto qualified_name_or_err = DOM::validate_and_extract(m_document->realm(), m_namespace, MUST(FlyString::from_deprecated_fly_string(name)));
+
+    if (qualified_name_or_err.is_error()) {
+        m_has_error = true;
+        return;
+    }
+
+    auto qualified_name = qualified_name_or_err.value();
+
+    auto node_or_err = DOM::create_element(m_document, qualified_name.local_name(), qualified_name.namespace_(), qualified_name.prefix());
+
+    if (node_or_err.is_error()) {
+        m_has_error = true;
+        return;
+    }
+
+    auto node = node_or_err.value();
 
     // When an XML parser with XML scripting support enabled creates a script element,
     // it must have its parser document set and its "force async" flag must be unset.