diff --git a/browser/base/content/test/general/browser_lastAccessedTab.js b/browser/base/content/test/general/browser_lastAccessedTab.js
index 4d788092a897..d0ad8b4cd323 100644
--- a/browser/base/content/test/general/browser_lastAccessedTab.js
+++ b/browser/base/content/test/general/browser_lastAccessedTab.js
@@ -17,7 +17,9 @@ function test() {
   gBrowser.selectedTab = newTab;
   let newTabAccessedDate = newTab.lastAccessed;
   ok(newTabAccessedDate > 0, "Timestamp on the selected tab is more than 0.");
-  ok(newTabAccessedDate <= Date.now(), "Timestamp less than or equal current Date.");
+  // Date.now is not guaranteed to be monotonic, so include one second of fudge.
+  let now = Date.now() + 1000;
+  ok(newTabAccessedDate <= now, "Timestamp less than or equal current Date: " + newTabAccessedDate + " <= " + now);
   gBrowser.selectedTab = originalTab;
   is(newTab.lastAccessed, newTabAccessedDate, "New tab's timestamp remains the same.");
   gBrowser.removeTab(newTab);
diff --git a/browser/devtools/debugger/debugger-view.js b/browser/devtools/debugger/debugger-view.js
index cf2c10df9f8f..8940863fa451 100644
--- a/browser/devtools/debugger/debugger-view.js
+++ b/browser/devtools/debugger/debugger-view.js
@@ -36,9 +36,6 @@ const DEFAULT_EDITOR_CONFIG = {
   showOverviewRuler: true
 };
 
-//For telemetry
-Cu.import("resource://gre/modules/Services.jsm")
-
 /**
  * Object defining the debugger view components.
  */
@@ -279,13 +276,10 @@ let DebuggerView = {
     if (this._editorSource.url == aSource.url && !aFlags.force) {
       return this._editorSource.promise;
     }
-    let transportType = DebuggerController.client.localTransport
-      ? "_LOCAL"
-      : "_REMOTE";
-    //Telemetry probe
+    let transportType = gClient.localTransport ? "_LOCAL" : "_REMOTE";
     let histogramId = "DEVTOOLS_DEBUGGER_DISPLAY_SOURCE" + transportType + "_MS";
     let histogram = Services.telemetry.getHistogramById(histogramId);
-    let startTime = +new Date();
+    let startTime = Date.now();
 
     let deferred = promise.defer();
 
@@ -306,7 +300,7 @@ let DebuggerView = {
       DebuggerView.Sources.selectedValue = aSource.url;
       DebuggerController.Breakpoints.updateEditorBreakpoints();
 
-      histogram.add(+new Date() - startTime);
+      histogram.add(Date.now() - startTime);
 
       // Resolve and notify that a source file was shown.
       window.emit(EVENTS.SOURCE_SHOWN, aSource);