diff --git a/components/site-search/template.njk b/components/site-search/template.njk
index 04ee6d3c..88983d57 100644
--- a/components/site-search/template.njk
+++ b/components/site-search/template.njk
@@ -1,4 +1,4 @@
-<site-search class="app-site-search govuk-!-display-none-print" index="{{ params.indexPath | htmlBaseUrl }}" label="{{ params.label | default("Search site") }}">
+<site-search class="app-site-search govuk-!-display-none-print" index="{{ params.indexPath | canonicalUrl }}" label="{{ params.label | default("Search site") }}">
 {%- if params.sitemapPath -%}
   <a class="app-site-search__link" href="{{ params.sitemapPath }}">Sitemap</a>
 {%- endif -%}
diff --git a/lib/filters/canonical-url.js b/lib/filters/canonical-url.js
index d1829b5a..c9a242ee 100644
--- a/lib/filters/canonical-url.js
+++ b/lib/filters/canonical-url.js
@@ -6,14 +6,19 @@ const path = require('node:path')
  * @returns {string} Canonical site URL with resolved path
  */
 module.exports = function (string = '') {
-  const { url } = this.ctx.options
+  const { options } = this.ctx
+
+  // No site URL configured
+  if (!options?.url) {
+    return string
+  }
 
   // If plugin options do not provide a site URL, return the path
-  if (!URL.canParse(url)) {
+  if (!URL.canParse(options.url)) {
     return string
   }
 
-  const siteUrl = new URL(url)
+  const siteUrl = new URL(options.url)
 
   // If incoming string is a URL, return that if it’s an external URL
   if (URL.canParse(string)) {