1 files changed, 3 insertions, 3 deletions
diff --git a/toolkit/content/widgets/datetimepicker.xml b/toolkit/content/widgets/datetimepicker.xml
index 5f16f1ff0..1d6a5e772 100644
--- a/toolkit/content/widgets/datetimepicker.xml
+++ b/toolkit/content/widgets/datetimepicker.xml
@@ -999,13 +999,13 @@
         <body>
           <![CDATA[
             var locale = Intl.DateTimeFormat().resolvedOptions().locale + "-u-ca-gregory";
-            var dtfMonth = Intl.DateTimeFormat(locale, {month: "long"});
+            var dtfMonth = Intl.DateTimeFormat(locale, {month: "long", timeZone: "UTC"});
             var dtfWeekday = Intl.DateTimeFormat(locale, {weekday: "narrow"});
 
             var monthLabel = this.monthField.firstChild;
-            var tempDate = new Date(2005, 0, 1);
+            var tempDate = new Date(Date.UTC(2005, 0, 1));
             for (var month = 0; month < 12; month++) {
-              tempDate.setMonth(month);
+              tempDate.setUTCMonth(month);
               monthLabel.setAttribute("value", dtfMonth.format(tempDate));
               monthLabel = monthLabel.nextSibling;
             }