diff --git a/lib/Sentry.js b/lib/Sentry.js
index 07b1700470..683198135f 100644
--- a/lib/Sentry.js
+++ b/lib/Sentry.js
@@ -49,7 +49,7 @@ export const Sentry = {
   },
 
   config(dsn, options) {
-    if (dsn.constructor !== String) {
+    if (typeof dsn !== 'string') {
       throw new Error('Sentry: A DSN must be provided');
     }
     Sentry._dsn = dsn;