--- a/calendar/test/unit/test_datetimeformatter.js
+++ b/calendar/test/unit/test_datetimeformatter.js
@@ -38,18 +38,18 @@ add_task(function* formatDate_test() {
 
 
     let tzs = cal.getTimezoneService();
 
     let i = 0;
     for (let test of data) {
         i++;
         Preferences.set("calendar.date.format", test.input.dateformat);
-        let tz = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
-        let date = cal.createDateTime(test.input.datetime).getInTimezone(tz);
+        let zone = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
+        let date = cal.createDateTime(test.input.datetime).getInTimezone(zone);
 
         let dtFormatter = Components.classes["@mozilla.org/calendar/datetime-formatter;1"]
                                     .getService(Components.interfaces.calIDateTimeFormatter);
         let formatted = dtFormatter.formatDate(date);
         ok(
             test.expected.includes(formatted),
             "(test #" + i + ": result '" + formatted + "', expected '" + test.expected + "')"
         );
@@ -117,18 +117,18 @@ add_task(function* formatDateShort_test(
     Preferences.set("calendar.date.format", 0);
 
     let tzs = cal.getTimezoneService();
 
     let i = 0;
     for (let test of data) {
         i++;
 
-        let tz = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
-        let date = cal.createDateTime(test.input.datetime).getInTimezone(tz);
+        let zone = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
+        let date = cal.createDateTime(test.input.datetime).getInTimezone(zone);
 
         let dtFormatter = Components.classes["@mozilla.org/calendar/datetime-formatter;1"]
                                     .getService(Components.interfaces.calIDateTimeFormatter);
 
         let formatted = dtFormatter.formatDateShort(date);
         ok(
             test.expected.includes(formatted),
             "(test #" + i + ": result '" + formatted + "', expected '" + test.expected + "')"
@@ -197,18 +197,18 @@ add_task(function* formatDateLong_test()
     Preferences.set("calendar.date.format", 1);
 
     let tzs = cal.getTimezoneService();
 
     let i = 0;
     for (let test of data) {
         i++;
 
-        let tz = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
-        let date = cal.createDateTime(test.input.datetime).getInTimezone(tz);
+        let zone = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
+        let date = cal.createDateTime(test.input.datetime).getInTimezone(zone);
 
         let dtFormatter = Components.classes["@mozilla.org/calendar/datetime-formatter;1"]
                                     .getService(Components.interfaces.calIDateTimeFormatter);
 
         let formatted = dtFormatter.formatDateLong(date);
         ok(
             test.expected.includes(formatted),
             "(test #" + i + ": result '" + formatted + "', expected '" + test.expected + "')"
@@ -277,18 +277,18 @@ add_task(function* formatDateWithoutYear
     Preferences.set("calendar.date.format", 1);
 
     let tzs = cal.getTimezoneService();
 
     let i = 0;
     for (let test of data) {
         i++;
 
-        let tz = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
-        let date = cal.createDateTime(test.input.datetime).getInTimezone(tz);
+        let zone = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
+        let date = cal.createDateTime(test.input.datetime).getInTimezone(zone);
 
         let dtFormatter = Components.classes["@mozilla.org/calendar/datetime-formatter;1"]
                                     .getService(Components.interfaces.calIDateTimeFormatter);
 
         equal(dtFormatter.formatDateWithoutYear(date), test.expected, "(test #" + i + ")");
     }
     // let's reset the preferences
     Preferences.set("calendar.timezone.local", tzlocal);
@@ -332,18 +332,18 @@ add_task(function* formatTime_test() {
     Preferences.set("calendar.timezone.local", "Pacific/Fakaofo");
 
     let tzs = cal.getTimezoneService();
 
     let i = 0;
     for (let test of data) {
         i++;
 
-        let tz = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
-        let date = cal.createDateTime(test.input.datetime).getInTimezone(tz);
+        let zone = (test.input.timezone == 'floating') ? cal.floating() : tzs.getTimezone(test.input.timezone);
+        let date = cal.createDateTime(test.input.datetime).getInTimezone(zone);
 
         let dtFormatter = Components.classes["@mozilla.org/calendar/datetime-formatter;1"]
                                     .getService(Components.interfaces.calIDateTimeFormatter);
 
         let formatted = dtFormatter.formatTime(date);
         ok(
             test.expected.includes(formatted),
             "(test #" + i + ": result '" + formatted + "', expected '" + test.expected + "')"