diff --git a/oauth3.core.js b/oauth3.core.js
index 05dfe49..cc2a623 100644
--- a/oauth3.core.js
+++ b/oauth3.core.js
@@ -1030,7 +1030,7 @@
             resolve();
           });
           img.addEventListener('error', function () {
-            var err = new Error("not an oauth3 issuer");
+            var err = new Error("OAuth3 support not detected: '" + url + "' not found");
             err.code = 'E_NOT_SUPPORTED';
             reject(err);
           });