diff --git a/packages/taler-util/src/payto.ts b/packages/taler-util/src/payto.ts
index 8eb0b88a8..1ac081a76 100644
--- a/packages/taler-util/src/payto.ts
+++ b/packages/taler-util/src/payto.ts
@@ -81,13 +81,12 @@ export function addPaytoQueryParams(
  * @returns
  */
 export function stringifyPaytoUri(p: PaytoUri): string {
-  const url = `${paytoPfx}${p.targetType}/${p.targetPath}`;
+  const url = new URL(`${paytoPfx}${p.targetType}/${p.targetPath}`);
   const paramList = !p.params ? [] : Object.entries(p.params);
-  if (paramList.length > 0) {
-    const search = paramList.map(([key, value]) => `${key}=${value}`).join("&");
-    return `${url}?${search}`;
-  }
-  return url;
+  paramList.forEach(([key, value]) => {
+    url.searchParams.set(key, value)
+  })
+  return url.href;
 }
 
 /**