diff --git a/unpacked/jax/output/HTML-CSS/jax.js b/unpacked/jax/output/HTML-CSS/jax.js
index 3eb7479da..4e8523d4e 100644
--- a/unpacked/jax/output/HTML-CSS/jax.js
+++ b/unpacked/jax/output/HTML-CSS/jax.js
@@ -522,7 +522,7 @@
       if (this.defaultEm) return;
       var ready = MathJax.Callback();
       AJAX.timer.start(AJAX,function (check) {
-        if (check.time(ready)) {HUB.signal.Post("HTML-CSS Jax - no default em size"); return}
+        if (check.time(ready)) {HUB.signal.Post(["HTML-CSS Jax - no default em size"]); return}
         HTMLCSS.getDefaultExEm();
         if (HTMLCSS.defaultEm) {ready()} else {setTimeout(check,check.delay)}
       },this.defaultEmDelay,this.defaultEmTimeout);