diff --git a/src/DateUtils.js b/src/DateUtils.js
index 0bce7c8a16..545d92dd3b 100644
--- a/src/DateUtils.js
+++ b/src/DateUtils.js
@@ -60,7 +60,7 @@ function twelveHourTime(date) {
 }
 
 module.exports = {
-    formatDate: function(date) {
+    formatDate: function(date, showTwelveHour=false) {
         var now = new Date();
         const days = getDaysArray();
         const months = getMonthsArray();
@@ -69,7 +69,7 @@ module.exports = {
         }
         else if (now.getTime() - date.getTime() < 6 * 24 * 60 * 60 * 1000) {
             // TODO: use standard date localize function provided in counterpart
-            return _t('%(weekDayName)s %(time)s', {weekDayName: days[date.getDay()], time: this.formatTime(date)});
+            return _t('%(weekDayName)s %(time)s', {weekDayName: days[date.getDay()], time: this.formatTime(date, showTwelveHour)});
         }
         else if (now.getFullYear() === date.getFullYear()) {
             // TODO: use standard date localize function provided in counterpart
@@ -80,7 +80,7 @@ module.exports = {
                 time: this.formatTime(date),
             });
         }
-        return this.formatFullDate(date);
+        return this.formatFullDate(date, showTwelveHour);
     },
 
     formatFullDate: function(date, showTwelveHour=false) {
diff --git a/src/components/views/rooms/EventTile.js b/src/components/views/rooms/EventTile.js
index 5c970a0966..170925999d 100644
--- a/src/components/views/rooms/EventTile.js
+++ b/src/components/views/rooms/EventTile.js
@@ -336,6 +336,7 @@ module.exports = WithMatrixClient(React.createClass({
                     suppressAnimation={this._suppressReadReceiptAnimation}
                     onClick={this.toggleAllReadAvatars}
                     timestamp={receipt.ts}
+                    showTwelveHour={this.props.isTwelveHour}
                 />
             );
         }
diff --git a/src/components/views/rooms/ReadReceiptMarker.js b/src/components/views/rooms/ReadReceiptMarker.js
index 7565b0741d..64b54fe1e1 100644
--- a/src/components/views/rooms/ReadReceiptMarker.js
+++ b/src/components/views/rooms/ReadReceiptMarker.js
@@ -66,6 +66,9 @@ module.exports = React.createClass({
 
         // Timestamp when the receipt was read
         timestamp: React.PropTypes.number,
+
+        // True to show twelve hour format, false otherwise
+        showTwelveHour: React.PropTypes.bool,
     },
 
     getDefaultProps: function() {
@@ -172,7 +175,7 @@ module.exports = React.createClass({
         if (this.props.timestamp) {
             title = _t(
                 "Seen by %(userName)s at %(dateTime)s",
-                {userName: this.props.member.userId, dateTime: DateUtils.formatDate(new Date(this.props.timestamp))}
+                {userName: this.props.member.userId, dateTime: DateUtils.formatDate(new Date(this.props.timestamp), this.props.showTwelveHour)}
             );
         }