1 files changed, 2 insertions, 0 deletions
diff --git a/src/preamble.js b/src/preamble.js
index bff5b91a..133e2669 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -42,6 +42,8 @@ var START_TIME = Date.now();
 
 var ABORT = false;
 
+var undef = 0;
+
 function assert(condition, text) {
   if (!condition) {
     var text = "Assertion failed: " + text;