diff --git a/generators/javascript.js b/generators/javascript.js
index 5bd49f9d2..cde1709e5 100644
--- a/generators/javascript.js
+++ b/generators/javascript.js
@@ -103,6 +103,12 @@ Blockly.JavaScript.ORDER_ASSIGNMENT = 16;    // = += -= *= /= %= <<= >>= ...
 Blockly.JavaScript.ORDER_COMMA = 17;         // ,
 Blockly.JavaScript.ORDER_NONE = 99;          // (...)
 
+/**
+ * Allow for switching between one and zero based indexing, one based by
+ * default.
+ */
+Blockly.JavaScript.ONE_BASED_INDEXING = true;
+
 /**
  * Initialise the database of variable names.
  * @param {!Blockly.Workspace} workspace Workspace to generate code from.