diff --git a/lib/models/room-member.js b/lib/models/room-member.js
index d27ea3a31..faad4253b 100644
--- a/lib/models/room-member.js
+++ b/lib/models/room-member.js
@@ -134,6 +134,12 @@ RoomMember.prototype._updateModifiedTime = function() {
     this._modified = Date.now();
 };
 
+/**
+ * Get the timestamp when this RoomMember was last updated. This timestamp is
+ * updated when properties on this RoomMember are updated.
+ * It is updated <i>before</i> firing events.
+ * @return {number} The timestamp
+ */
 RoomMember.prototype.getLastModifiedTime = function() {
     return this._modified;
 };
diff --git a/lib/models/room-state.js b/lib/models/room-state.js
index 45ef26512..0f295423b 100644
--- a/lib/models/room-state.js
+++ b/lib/models/room-state.js
@@ -30,6 +30,7 @@ function RoomState(roomId) {
     this._sentinels = {
         // userId: RoomMember
     };
+    this._updateModifiedTime();
 }
 utils.inherits(RoomState, EventEmitter);
 
@@ -96,6 +97,7 @@ RoomState.prototype.getStateEvents = function(eventType, stateKey) {
  */
 RoomState.prototype.setStateEvents = function(stateEvents) {
     var self = this;
+    this._updateModifiedTime();
 
     // update the core event dict
     utils.forEach(stateEvents, function(event) {
@@ -162,6 +164,19 @@ RoomState.prototype.setTypingEvent = function(event) {
     });
 };
 
+RoomState.prototype._updateModifiedTime = function() {
+    this._modified = Date.now();
+};
+
+/**
+ * Get the timestamp when this room state was last updated. This timestamp is
+ * updated when this object has received new state events.
+ * @return {number} The timestamp
+ */
+RoomState.prototype.getLastModifiedTime = function() {
+    return this._modified;
+};
+
 /**
  * The RoomState class.
  */
diff --git a/lib/models/user.js b/lib/models/user.js
index fff6e2322..0d87221e4 100644
--- a/lib/models/user.js
+++ b/lib/models/user.js
@@ -78,6 +78,12 @@ User.prototype._updateModifiedTime = function() {
     this._modified = Date.now();
 };
 
+/**
+ * Get the timestamp when this User was last updated. This timestamp is
+ * updated when this User receives a new Presence event which has updated a
+ * property on this object. It is updated <i>before</i> firing events.
+ * @return {number} The timestamp
+ */
 User.prototype.getLastModifiedTime = function() {
     return this._modified;
 };