diff --git a/IPython/html/static/notebook/js/widgets/widget.js b/IPython/html/static/notebook/js/widgets/widget.js
index 5b4c3de..f98aa97 100644
--- a/IPython/html/static/notebook/js/widgets/widget.js
+++ b/IPython/html/static/notebook/js/widgets/widget.js
@@ -54,7 +54,7 @@ function(WidgetManager, Underscore, Backbone){
         send: function (content, callbacks) {
             // Send a custom msg over the comm.
             if (this.comm !== undefined) {
-                var data = {method: 'custom', custom_content: content};
+                var data = {method: 'custom', content: content};
                 this.comm.send(data, callbacks);
             }
         },
@@ -76,7 +76,7 @@ function(WidgetManager, Underscore, Backbone){
                     this.apply_update(msg.content.data.state);
                     break;
                 case 'custom':
-                    this.trigger('msg:custom', msg.content.data.custom_content);
+                    this.trigger('msg:custom', msg.content.data.content);
                     break;
                 case 'display':
                     this.widget_manager.display_view(msg, this);
diff --git a/IPython/html/widgets/widget.py b/IPython/html/widgets/widget.py
index 4a9c996..a88b502 100644
--- a/IPython/html/widgets/widget.py
+++ b/IPython/html/widgets/widget.py
@@ -153,7 +153,7 @@ class Widget(LoggingConfigurable):
         content : dict
             Content of the message to send.
         """
-        self._send({"method": "custom", "custom_content": content})
+        self._send({"method": "custom", "content": content})
 
     def on_msg(self, callback, remove=False):
         """(Un)Register a custom msg recieve callback.
@@ -249,8 +249,8 @@ class Widget(LoggingConfigurable):
 
         # Handle a custom msg from the front-end
         elif method == 'custom':
-            if 'custom_content' in data:
-                self._handle_custom_msg(data['custom_content'])
+            if 'content' in data:
+                self._handle_custom_msg(data['content'])
 
     def _handle_receive_state(self, sync_data):
         """Called when a state is received from the front-end."""