--- a/accessible/tests/browser/e10s/events.js
+++ b/accessible/tests/browser/e10s/events.js
@@ -63,17 +63,21 @@ function waitForEvent(eventType, expecte
   return new Promise(resolve => {
     let eventObserver = {
       observe(subject, topic, data) {
         if (topic !== 'accessible-event') {
           return;
         }
 
         let event = subject.QueryInterface(nsIAccessibleEvent);
-        Logger.log(eventToString(event));
+        if (Logger.enabled) {
+          // Avoid calling eventToString if the logger isn't enabled in order
+          // to avoid an intermittent crash (bug 1307645).
+          Logger.log(eventToString(event));
+        }
 
         // If event type does not match expected type, skip the event.
         if (event.eventType !== eventType) {
           return;
         }
 
         let acc = event.accessible;
         let id = getAccessibleDOMNodeID(acc);