diff --git a/src/dom/parse.js b/src/dom/parse.js
index d42e33e..6358922 100644
--- a/src/dom/parse.js
+++ b/src/dom/parse.js
@@ -590,7 +590,9 @@ wysihtml5.dom.parse = function(elementOrHtml_current, config_current) {
           attributes["class"] = oldNode.getAttribute("class");
         }
       } else {
-        attributes["class"] = wysihtml5.lang.array(classes).unique().join(" ");
+        if(classes && classes.length > 0) {
+          attributes["class"] = wysihtml5.lang.array(classes).unique().join(" ");
+        }
       }
     } else {
       // make sure that wysihtml5 temp class doesn't get stripped out