diff --git a/HISTORY.md b/HISTORY.md
index d6ec921..90b455a 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -3,11 +3,17 @@
 https://github.com/josdejong/jsoneditor
 
 
+## not yet published, version 5.28.2
+
+- Fix #639: Occurrence of non-ES5 `const` declaration in published code.
+  Regression introduced in `v5.28.0`.
+
+
 ## 2019-01-22, version 5.28.1
 
-- Fix #637: vertical white border left/right from the main menu in some
+- Fix #637: Vertical white border left/right from the main menu in some
   specific circumstances.
-- Fix #638: cannot expand after collapse. Regression introduced in v5.28.0.
+- Fix #638: Cannot expand after collapse. Regression introduced in v5.28.0.
 
 
 ## 2019-01-21, version 5.28.0
diff --git a/src/js/Node.js b/src/js/Node.js
index d427dc5..290d65e 100644
--- a/src/js/Node.js
+++ b/src/js/Node.js
@@ -925,7 +925,7 @@ Node.prototype._updateCssClassName = function () {
     && typeof this.editor.options.onClassName ==='function'
     && this.dom.tree){              
       util.removeAllClassNames(this.dom.tree);              
-      const addClasses = this.editor.options.onClassName({ path: this.getPath(), field: this.field, value: this.value }) || "";      
+      var addClasses = this.editor.options.onClassName({ path: this.getPath(), field: this.field, value: this.value }) || "";
       util.addClassName(this.dom.tree, "jsoneditor-values " + addClasses);
   }
 };