diff --git a/lib/test.js b/lib/test.js
index e1b56686..bc463fcd 100644
--- a/lib/test.js
+++ b/lib/test.js
@@ -261,7 +261,8 @@ Test.prototype._assert = function assert(ok, opts) {
     this._ok = !!(this._ok && ok);
 
     if (!ok && !res.todo) {
-        res.error = defined(extra.error, opts.error, new Error(res.name));
+        var anError = res.name instanceof Error ? res.name : new Error(res.name);
+        res.error = defined(extra.error, opts.error, anError);
     }
 
     if (!ok) {