diff --git a/core/misc/machine-name.js b/core/misc/machine-name.js
index a7ba0f74d9942643c349bbe2eb80c66d2a9e8f3b..9ef6e47fe03f88de038fc0dd220833fc662d0f42 100644
--- a/core/misc/machine-name.js
+++ b/core/misc/machine-name.js
@@ -62,7 +62,7 @@ Drupal.behaviors.machineName = {
       if (settings.machineName.hasOwnProperty(source_id)) {
         options =  settings.machineName[source_id];
 
-        var $source = $context.find(source_id).addClass('machine-name-source');
+        var $source = $context.find(source_id).addClass('machine-name-source').once('machine-name');
         var $target = $context.find(options.target).addClass('machine-name-target');
         var $suffix = $context.find(options.suffix);
         var $wrapper = $target.closest('.form-item');