diff --git a/core/registry.js b/core/registry.js
index 1be9b2a2b..5752702ae 100644
--- a/core/registry.js
+++ b/core/registry.js
@@ -137,7 +137,7 @@ const register = function(type, name, registryItem, opt_allowOverrides) {
       String(type).trim() == '') {
     throw Error(
         'Invalid type "' + type + '". The type must be a' +
-        ' non-empty string or a Type.');
+        ' non-empty string or a Blockly.registry.Type.');
   }
   type = String(type).toLowerCase();