--- a/testing/marionette/listener.js
+++ b/testing/marionette/listener.js
@@ -33,16 +33,17 @@ const {
   NoSuchFrameError,
   pprint,
   TimeoutError,
   UnknownError,
 } = Cu.import("chrome://marionette/content/error.js", {});
 Cu.import("chrome://marionette/content/evaluate.js");
 Cu.import("chrome://marionette/content/event.js");
 const {ContentEventObserverService} = Cu.import("chrome://marionette/content/dom.js", {});
+const {truncate} = Cu.import("chrome://marionette/content/format.js", {});
 Cu.import("chrome://marionette/content/interaction.js");
 Cu.import("chrome://marionette/content/legacyaction.js");
 Cu.import("chrome://marionette/content/navigate.js");
 Cu.import("chrome://marionette/content/proxy.js");
 Cu.import("chrome://marionette/content/session.js");
 
 Cu.importGlobalProperties(["URL"]);
 
@@ -154,17 +155,17 @@ const loadListener = {
     } else {
       // The frame script got reloaded due to a new content process.
       // Due to the time it takes to re-register the browser in Marionette,
       // it can happen that page load events are missed before the listeners
       // are getting attached again. By checking the document readyState the
       // command can return immediately if the page load is already done.
       let readyState = content.document.readyState;
       let documentURI = content.document.documentURI;
-      logger.debug(`Check readyState "${readyState} for "${documentURI}"`);
+      logger.debug(truncate`Check readyState ${readyState} for ${documentURI}`);
       // If the page load has already finished, don't setup listeners and
       // timers but return immediatelly.
       if (this.handleReadyState(readyState, documentURI)) {
         return;
       }
 
       addEventListener("DOMContentLoaded", loadListener, true);
       addEventListener("pageshow", loadListener, true);
@@ -208,17 +209,17 @@ const loadListener = {
     // Only care about events from the currently selected browsing context,
     // whereby some of those do not bubble up to the window.
     if (event.target != curContainer.frame &&
         event.target != curContainer.frame.document) {
       return;
     }
 
     let location = event.target.documentURI || event.target.location.href;
-    logger.debug(`Received DOM event "${event.type}" for "${location}"`);
+    logger.debug(truncate`Received DOM event ${event.type} for ${location}`);
 
     switch (event.type) {
       case "beforeunload":
         this.seenBeforeUnload = true;
         break;
 
       case "unload":
         this.seenUnload = true;
@@ -347,17 +348,17 @@ const loadListener = {
   },
 
   observe(subject, topic) {
     const win = curContainer.frame;
     const winID = subject.QueryInterface(Ci.nsISupportsPRUint64).data;
     const curWinID = win.QueryInterface(Ci.nsIInterfaceRequestor)
         .getInterface(Ci.nsIDOMWindowUtils).outerWindowID;
 
-    logger.debug(`Received observer notification "${topic}" for "${winID}"`);
+    logger.debug(`Received observer notification ${topic} for ${winID}`);
 
     switch (topic) {
       // In the case when the currently selected frame is closed,
       // there will be no further load events. Stop listening immediately.
       case "outer-window-destroyed":
         if (curWinID === winID) {
           this.stop();
           sendOk(this.commandID);
@@ -1623,17 +1624,17 @@ async function reftestWait(url, remote) 
 
   let windowUtils = content.QueryInterface(Ci.nsIInterfaceRequestor)
       .getInterface(Ci.nsIDOMWindowUtils);
 
 
   let reftestWait = false;
 
   if (document.location.href !== url || document.readyState != "complete") {
-    logger.debug(`Waiting for page load of ${url}`);
+    logger.debug(truncate`Waiting for page load of ${url}`);
     await new Promise(resolve => {
       let maybeResolve = event => {
         if (event.target === curContainer.frame.document &&
             event.target.location.href === url) {
           win = curContainer.frame;
           document = curContainer.frame.document;
           reftestWait = document.documentElement.classList.contains("reftest-wait");
           removeEventListener("load", maybeResolve, {once: true});