diff --git a/lib/server.js b/lib/server.js
index ab72b21c..619e398e 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -92,7 +92,8 @@ exports.toCanvas = require('./browser').toCanvas
 
 exports.toString = function toString (text, opts, cb) {
   const params = checkParams(text, opts, cb)
-  const renderer = getStringRendererFromType(params.opts.type)
+  const type = params.opts ? params.opts.type : undefined
+  const renderer = getStringRendererFromType(type)
   return render(renderer.render, text, params)
 }