diff --git a/app/src/main/java/im/vector/riotredesign/core/extensions/Iterable.kt b/app/src/main/java/im/vector/riotredesign/core/extensions/Iterable.kt
new file mode 100644
index 0000000000..092a94ac6e
--- /dev/null
+++ b/app/src/main/java/im/vector/riotredesign/core/extensions/Iterable.kt
@@ -0,0 +1,38 @@
+/*
+ *
+ *  * Copyright 2019 New Vector Ltd
+ *  *
+ *  * Licensed under the Apache License, Version 2.0 (the "License");
+ *  * you may not use this file except in compliance with the License.
+ *  * You may obtain a copy of the License at
+ *  *
+ *  *     http://www.apache.org/licenses/LICENSE-2.0
+ *  *
+ *  * Unless required by applicable law or agreed to in writing, software
+ *  * distributed under the License is distributed on an "AS IS" BASIS,
+ *  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  * See the License for the specific language governing permissions and
+ *  * limitations under the License.
+ *
+ */
+
+package im.vector.riotredesign.core.extensions
+
+/**
+ * Returns the last element yielding the smallest value of the given function or `null` if there are no elements.
+ */
+public inline fun <T, R : Comparable<R>> Iterable<T>.lastMinBy(selector: (T) -> R): T? {
+    val iterator = iterator()
+    if (!iterator.hasNext()) return null
+    var minElem = iterator.next()
+    var minValue = selector(minElem)
+    while (iterator.hasNext()) {
+        val e = iterator.next()
+        val v = selector(e)
+        if (minValue >= v) {
+            minElem = e
+            minValue = v
+        }
+    }
+    return minElem
+}
\ No newline at end of file
diff --git a/app/src/main/java/im/vector/riotredesign/features/home/room/detail/RoomDetailViewModel.kt b/app/src/main/java/im/vector/riotredesign/features/home/room/detail/RoomDetailViewModel.kt
index abdf1a1c8c..3d1d4cf104 100644
--- a/app/src/main/java/im/vector/riotredesign/features/home/room/detail/RoomDetailViewModel.kt
+++ b/app/src/main/java/im/vector/riotredesign/features/home/room/detail/RoomDetailViewModel.kt
@@ -24,6 +24,7 @@ import im.vector.matrix.android.api.MatrixCallback
 import im.vector.matrix.android.api.session.Session
 import im.vector.matrix.android.api.session.events.model.Event
 import im.vector.matrix.rx.rx
+import im.vector.riotredesign.core.extensions.lastMinBy
 import im.vector.riotredesign.core.platform.RiotViewModel
 import im.vector.riotredesign.features.home.room.VisibleRoomHolder
 import io.reactivex.rxkotlin.subscribeBy
@@ -86,12 +87,12 @@ class RoomDetailViewModel(initialState: RoomDetailViewState,
         displayedEventsObservable.hide()
                 .buffer(1, TimeUnit.SECONDS)
                 .filter { it.isNotEmpty() }
-                .subscribeBy { actions ->
-                    val mostRecentEvent = actions.minBy { it.index }
+                .subscribeBy(onNext = { actions ->
+                    val mostRecentEvent = actions.lastMinBy { it.index }
                     mostRecentEvent?.event?.root?.eventId?.let { eventId ->
                         room.setReadReceipt(eventId, callback = object : MatrixCallback<Void> {})
                     }
-                }
+                })
                 .disposeOnClear()
     }
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/read/SetReadMarkersTask.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/read/SetReadMarkersTask.kt
index 92e44155a8..f127966d3d 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/read/SetReadMarkersTask.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/read/SetReadMarkersTask.kt
@@ -18,6 +18,7 @@ package im.vector.matrix.android.internal.session.room.read
 
 import arrow.core.Try
 import com.zhuinden.monarchy.Monarchy
+import im.vector.matrix.android.api.MatrixPatterns
 import im.vector.matrix.android.api.auth.data.Credentials
 import im.vector.matrix.android.internal.database.model.ChunkEntity
 import im.vector.matrix.android.internal.database.model.EventEntity
@@ -51,10 +52,13 @@ internal class DefaultSetReadMarkersTask(private val roomAPI: RoomAPI,
 
     override fun execute(params: SetReadMarkersTask.Params): Try<Unit> {
         val markers = HashMap<String, String>()
-        if (params.fullyReadEventId?.isNotEmpty() == true) {
+        if (params.fullyReadEventId != null && MatrixPatterns.isEventId(params.fullyReadEventId)) {
             markers[READ_MARKER] = params.fullyReadEventId
         }
-        if (params.readReceiptEventId?.isNotEmpty() == true && !isEventRead(params.roomId, params.readReceiptEventId)) {
+        if (params.readReceiptEventId != null
+                && MatrixPatterns.isEventId(params.readReceiptEventId)
+                && !isEventRead(params.roomId, params.readReceiptEventId)) {
+
             updateNotificationCountIfNecessary(params.roomId, params.readReceiptEventId)
             markers[READ_RECEIPT] = params.readReceiptEventId
         }
@@ -72,7 +76,7 @@ internal class DefaultSetReadMarkersTask(private val roomAPI: RoomAPI,
             val isLatestReceived = EventEntity.latestEvent(realm, eventId)?.eventId == eventId
             if (isLatestReceived) {
                 val roomSummary = RoomSummaryEntity.where(realm, roomId).findFirst()
-                                  ?: return@tryTransactionAsync
+                        ?: return@tryTransactionAsync
                 roomSummary.notificationCount = 0
                 roomSummary.highlightCount = 0
             }
@@ -83,11 +87,11 @@ internal class DefaultSetReadMarkersTask(private val roomAPI: RoomAPI,
         var isEventRead = false
         monarchy.doWithRealm {
             val readReceipt = ReadReceiptEntity.where(it, roomId, credentials.userId).findFirst()
-                              ?: return@doWithRealm
+                    ?: return@doWithRealm
             val liveChunk = ChunkEntity.findLastLiveChunkFromRoom(it, roomId)
-                            ?: return@doWithRealm
+                    ?: return@doWithRealm
             val readReceiptIndex = liveChunk.events.find(readReceipt.eventId)?.displayIndex
-                                   ?: -1
+                    ?: -1
             val eventToCheckIndex = liveChunk.events.find(eventId)?.displayIndex ?: -1
             isEventRead = eventToCheckIndex >= readReceiptIndex
         }