diff --git a/lib/test-jig.js b/lib/test-jig.js
index <HASH>..<HASH> 100644
--- a/lib/test-jig.js
+++ b/lib/test-jig.js
@@ -16,7 +16,7 @@ function TestJig(rules, testData) {
 
 TestJig.prototype._lookupAuth = function(auth) {
 
-  if (this.users[auth] == null) {
+  if (this.users[auth] === null) {
     // Unauthenticated user
     auth = null;
   } else if (typeof auth === 'string') {
Changed == to === in test-jig.js