diff --git a/core/field_label.js b/core/field_label.js
index 5dc434c92..4a19dc07e 100644
--- a/core/field_label.js
+++ b/core/field_label.js
@@ -64,7 +64,7 @@ Blockly.FieldLabel.prototype.DEFAULT_VALUE = '';
  * @nocollapse
  */
 Blockly.FieldLabel.fromJson = function(options) {
-  var text = Blockly.utils.replaceMessageReferences(options['text']);
+  const text = Blockly.utils.replaceMessageReferences(options['text']);
   // `this` might be a subclass of FieldLabel if that class doesn't override
   // the static fromJson method.
   return new this(text, undefined, options);