diff --git a/lib/toRdf.js b/lib/toRdf.js
index e8a54844..87972fcf 100644
--- a/lib/toRdf.js
+++ b/lib/toRdf.js
@@ -52,7 +52,7 @@ module.exports = api;
  */
 api.toRDF = (input, options) => {
   // create node map for default graph (and any named graphs)
-  const issuer = new util.IdentifierIssuer('_:b');
+  const issuer = options.issuer || new util.IdentifierIssuer('_:b');
   const nodeMap = {'@default': {}};
   createNodeMap(input, nodeMap, '@default', issuer);