diff --git a/core/field_textdropdown.js b/core/field_textdropdown.js
index 2736f5c302..2717831b81 100644
--- a/core/field_textdropdown.js
+++ b/core/field_textdropdown.js
@@ -133,6 +133,12 @@ Blockly.FieldTextDropdown.prototype.showEditor_ = function() {
   }
 };
 
+/**
+ * @return {boolean} True if the option list is generated by a function.
+ *     Otherwise false.
+ */
+Blockly.FieldTextDropdown.prototype.isOptionListDynamic = Blockly.FieldDropdown.prototype.isOptionListDynamic;
+
 /**
  * Return a list of the options for this dropdown.
  * See: Blockly.FieldDropDown.prototype.getOptions_.