2 files changed, 8 insertions, 2 deletions
diff --git a/toolkit/components/mozintl/mozIntl.sys.mjs b/toolkit/components/mozintl/mozIntl.sys.mjs
index 50633e365c..ad0b4dd5d9 100644
--- a/toolkit/components/mozintl/mozIntl.sys.mjs
+++ b/toolkit/components/mozintl/mozIntl.sys.mjs
@@ -143,7 +143,7 @@ function bestFit(absDiff) {
  * Thresholds to use for calculating the best unit for relative time fromatting.
  */
 const threshold = {
-  month: 2, // at least 2 months before using year.
+  month: 11, // at least 11 months before using year.
   week: 3, // at least 3 weeks before using month.
   day: 6, // at least 6 days before using week.
   hour: 6, // at least 6 hours before using day.
diff --git a/toolkit/components/mozintl/test/test_mozintl.js b/toolkit/components/mozintl/test/test_mozintl.js
index dc7b8a7afd..2ee1583b8c 100644
--- a/toolkit/components/mozintl/test/test_mozintl.js
+++ b/toolkit/components/mozintl/test/test_mozintl.js
@@ -139,6 +139,10 @@ function test_rtf_formatBestUnit() {
     let anchor = new Date("2016-04-10 12:00:00");
     testRTFBestUnit(anchor, "2014-04-01 00:00", "2 years ago");
     testRTFBestUnit(anchor, "2015-03-01 00:00", "last year");
+    testRTFBestUnit(anchor, "2015-04-01 00:00", "last year");
+    testRTFBestUnit(anchor, "2015-05-01 00:00", "11 months ago");
+    testRTFBestUnit(anchor, "2015-12-01 00:00", "4 months ago");
+    testRTFBestUnit(anchor, "2016-02-01 00:00", "2 months ago");
     testRTFBestUnit(anchor, "2017-05-01 00:00", "next year");
     testRTFBestUnit(anchor, "2024-12-01 23:59", "in 8 years");
 
@@ -147,8 +151,10 @@ function test_rtf_formatBestUnit() {
     testRTFBestUnit(anchor, "2015-12-29 18:30", "2 years ago");
 
     anchor = new Date("2016-12-29 18:30");
-    testRTFBestUnit(anchor, "2017-07-12 18:30", "next year");
     testRTFBestUnit(anchor, "2017-02-12 18:30", "in 2 months");
+    testRTFBestUnit(anchor, "2017-07-12 18:30", "in 7 months");
+    testRTFBestUnit(anchor, "2017-11-29 18:30", "in 11 months");
+    testRTFBestUnit(anchor, "2017-12-01 18:30", "next year");
     testRTFBestUnit(anchor, "2018-01-02 18:30", "in 2 years");
 
     testRTFBestUnit(anchor, "2098-01-02 18:30", "in 82 years");