diff --git a/externs/generator-externs.js b/externs/generator-externs.js
index a86531856..288c3aa2a 100644
--- a/externs/generator-externs.js
+++ b/externs/generator-externs.js
@@ -11,6 +11,7 @@
 
 goog.provide('Blockly');
 goog.provide('Blockly.Generator');
+goog.provide('Blockly.inputTypes');
 goog.provide('Blockly.utils.global');
 goog.provide('Blockly.utils.string');