diff --git a/Imager.js b/Imager.js
index <HASH>..<HASH> 100644
--- a/Imager.js
+++ b/Imager.js
@@ -80,14 +80,14 @@
         opts = opts || {};
 
         if (elements !== undefined) {
-            // selector
+            // first argument is selector string
             if (typeof elements === 'string') {
                 opts.selector = elements;
                 elements = undefined;
             }
 
-            // config object
-            else if (!elements.hasOwnProperty('length')) {
+            // first argument is the `opts` object, `elements` is implicitly the `opts.selector` string
+            else if (typeof elements.length === 'undefined') {
                 opts = elements;
                 elements = undefined;
             }
Fixing `length` check.

`hasOwnProperty('length')` is not supposed to work on an `NodeList` as it's an inherited property.