diff --git a/js/ui/messageTray.js b/js/ui/messageTray.js
index 9476d7aec..ef0d59395 100644
--- a/js/ui/messageTray.js
+++ b/js/ui/messageTray.js
@@ -792,11 +792,12 @@ Notification.prototype = {
     },
 
     _bannerBoxAllocate: function(actor, box, flags) {
-        let [titleMinW, titleNatW] = this._titleLabel.get_preferred_width(-1);
-        let [titleMinH, titleNatH] = this._titleLabel.get_preferred_height(-1);
-        let [bannerMinW, bannerNatW] = this._bannerLabel.get_preferred_width(-1);
         let availWidth = box.x2 - box.x1;
 
+        let [titleMinW, titleNatW] = this._titleLabel.get_preferred_width(-1);
+        let [titleMinH, titleNatH] = this._titleLabel.get_preferred_height(availWidth);
+        let [bannerMinW, bannerNatW] = this._bannerLabel.get_preferred_width(availWidth);
+
         let titleBox = new Clutter.ActorBox();
         let titleBoxW = Math.min(titleNatW, availWidth);
         if (this._titleDirection == St.TextDirection.RTL) {