diff --git a/lib/wysihtml/rails/version.rb b/lib/wysihtml/rails/version.rb
index 8aca0c4..4f59571 100644
--- a/lib/wysihtml/rails/version.rb
+++ b/lib/wysihtml/rails/version.rb
@@ -1,5 +1,5 @@
 module Wysihtml
   module Rails
-    VERSION = "0.5.0"
+    VERSION = "0.5.1"
   end
 end
diff --git a/vendor/assets/javascripts/wysihtml-toolbar.js b/vendor/assets/javascripts/wysihtml-toolbar.js
index 0e6e527..e8c5f61 100644
--- a/vendor/assets/javascripts/wysihtml-toolbar.js
+++ b/vendor/assets/javascripts/wysihtml-toolbar.js
@@ -1,5 +1,5 @@
 /**
- * @license wysihtml v0.5.0
+ * @license wysihtml v0.5.1
  * https://github.com/Voog/wysihtml
  *
  * Author: Christopher Blum (https://github.com/tiff)
@@ -10,7 +10,7 @@
  *
  */
 var wysihtml5 = {
-  version: "0.5.0",
+  version: "0.5.1",
 
   // namespaces
   commands:   {},
@@ -9164,7 +9164,9 @@ 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
diff --git a/vendor/assets/javascripts/wysihtml.js b/vendor/assets/javascripts/wysihtml.js
index 6a47fae..b14e8c5 100644
--- a/vendor/assets/javascripts/wysihtml.js
+++ b/vendor/assets/javascripts/wysihtml.js
@@ -1,5 +1,5 @@
 /**
- * @license wysihtml v0.5.0
+ * @license wysihtml v0.5.1
  * https://github.com/Voog/wysihtml
  *
  * Author: Christopher Blum (https://github.com/tiff)
@@ -10,7 +10,7 @@
  *
  */
 var wysihtml5 = {
-  version: "0.5.0",
+  version: "0.5.1",
 
   // namespaces
   commands:   {},
@@ -9164,7 +9164,9 @@ 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