diff --git a/lib/api.js b/lib/api.js
index c49b4d8..15a81f0 100644
--- a/lib/api.js
+++ b/lib/api.js
@@ -655,7 +655,7 @@ SearchForm.prototype = {
       return this.set("q", query);
     } else {
       var predicates;
-      if (query.constructor === Array && query.length > 0 && query[0].constructor === Array) {
+      if (Array.isArray(query) && query.length > 0 && Array.isArray(query[0])) {
         predicates = query;
       } else {
         predicates = [].slice.apply(arguments); // Convert to a real JS array