diff --git a/src/course-home/outline-tab/SequenceLink.jsx b/src/course-home/outline-tab/SequenceLink.jsx
index 863ef7a9..96c1c6d3 100644
--- a/src/course-home/outline-tab/SequenceLink.jsx
+++ b/src/course-home/outline-tab/SequenceLink.jsx
@@ -96,7 +96,7 @@ function SequenceLink({
                       day="numeric"
                       month="short"
                       year="numeric"
-                      hour12={false}
+                      hourCycle="h23"
                       timeZoneName="short"
                       value={due}
                       {...timezoneFormatArgs}
diff --git a/src/course-home/outline-tab/alerts/course-end-alert/CourseEndAlert.jsx b/src/course-home/outline-tab/alerts/course-end-alert/CourseEndAlert.jsx
index 858ff49f..b3298236 100644
--- a/src/course-home/outline-tab/alerts/course-end-alert/CourseEndAlert.jsx
+++ b/src/course-home/outline-tab/alerts/course-end-alert/CourseEndAlert.jsx
@@ -37,7 +37,7 @@ function CourseEndAlert({ payload }) {
         day="numeric"
         month="short"
         year="numeric"
-        hour12={false}
+        hourCycle="h23"
         timeZoneName="short"
         value={endDate}
         {...timezoneFormatArgs}
diff --git a/src/course-home/outline-tab/alerts/course-start-alert/CourseStartAlert.jsx b/src/course-home/outline-tab/alerts/course-start-alert/CourseStartAlert.jsx
index 8b69d664..873ac5be 100644
--- a/src/course-home/outline-tab/alerts/course-start-alert/CourseStartAlert.jsx
+++ b/src/course-home/outline-tab/alerts/course-start-alert/CourseStartAlert.jsx
@@ -42,7 +42,7 @@ function CourseStartAlert({ payload }) {
                 day="numeric"
                 month="short"
                 year="numeric"
-                hour12={false}
+                hourCycle="h23"
                 timeZoneName="short"
                 value={startDate}
                 {...timezoneFormatArgs}