diff --git a/matrix-sdk-android/src/androidTest/java/org/matrix/android/sdk/common/TestRoomDisplayNameFallbackProvider.kt b/matrix-sdk-android/src/androidTest/java/org/matrix/android/sdk/common/TestRoomDisplayNameFallbackProvider.kt
index c98bca42b9..af2d57f9ce 100644
--- a/matrix-sdk-android/src/androidTest/java/org/matrix/android/sdk/common/TestRoomDisplayNameFallbackProvider.kt
+++ b/matrix-sdk-android/src/androidTest/java/org/matrix/android/sdk/common/TestRoomDisplayNameFallbackProvider.kt
@@ -26,15 +26,18 @@ class TestRoomDisplayNameFallbackProvider : RoomDisplayNameFallbackProvider {
     override fun getNameForEmptyRoom(isDirect: Boolean, leftMemberNames: List<String>) =
             "Empty room"
 
-    override fun getNameFor2members(name1: String?, name2: String?) =
+    override fun getNameFor1member(name: String) =
+            name
+
+    override fun getNameFor2members(name1: String, name2: String) =
             "$name1 and $name2"
 
-    override fun getNameFor3members(name1: String?, name2: String?, name3: String?) =
+    override fun getNameFor3members(name1: String, name2: String, name3: String) =
             "$name1, $name2 and $name3"
 
-    override fun getNameFor4members(name1: String?, name2: String?, name3: String?, name4: String?) =
+    override fun getNameFor4members(name1: String, name2: String, name3: String, name4: String) =
             "$name1, $name2, $name3 and $name4"
 
-    override fun getNameFor4membersAndMore(name1: String?, name2: String?, name3: String?, remainingCount: Int) =
+    override fun getNameFor4membersAndMore(name1: String, name2: String, name3: String, remainingCount: Int) =
             "$name1, $name2, $name3 and $remainingCount others"
 }
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/RoomDisplayNameFallbackProvider.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/RoomDisplayNameFallbackProvider.kt
index b16d29c997..a34dbcc196 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/RoomDisplayNameFallbackProvider.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/RoomDisplayNameFallbackProvider.kt
@@ -19,8 +19,9 @@ package org.matrix.android.sdk.api
 interface RoomDisplayNameFallbackProvider {
     fun getNameForRoomInvite(): String
     fun getNameForEmptyRoom(isDirect: Boolean, leftMemberNames: List<String>): String
-    fun getNameFor2members(name1: String?, name2: String?): String
-    fun getNameFor3members(name1: String?, name2: String?, name3: String?): String
-    fun getNameFor4members(name1: String?, name2: String?, name3: String?, name4: String?): String
-    fun getNameFor4membersAndMore(name1: String?, name2: String?, name3: String?, remainingCount: Int): String
+    fun getNameFor1member(name: String): String
+    fun getNameFor2members(name1: String, name2: String): String
+    fun getNameFor3members(name1: String, name2: String, name3: String): String
+    fun getNameFor4members(name1: String, name2: String, name3: String, name4: String): String
+    fun getNameFor4membersAndMore(name1: String, name2: String, name3: String, remainingCount: Int): String
 }
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/membership/RoomDisplayNameResolver.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/membership/RoomDisplayNameResolver.kt
index 194134f45d..3aa812d93d 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/membership/RoomDisplayNameResolver.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/membership/RoomDisplayNameResolver.kt
@@ -112,7 +112,11 @@ internal class RoomDisplayNameResolver @Inject constructor(
                             .map { it.getBestName() }
                     roomDisplayNameFallbackProvider.getNameForEmptyRoom(roomSummary?.isDirect.orFalse(), leftMembersNames)
                 }
-                1    -> resolveRoomMemberName(otherMembersSubset[0], roomMembers)
+                1    -> {
+                    roomDisplayNameFallbackProvider.getNameFor1member(
+                            resolveRoomMemberName(otherMembersSubset[0], roomMembers)
+                    )
+                }
                 2    -> {
                     roomDisplayNameFallbackProvider.getNameFor2members(
                             resolveRoomMemberName(otherMembersSubset[0], roomMembers),
@@ -149,9 +153,8 @@ internal class RoomDisplayNameResolver @Inject constructor(
     }
 
     /** See [org.matrix.android.sdk.api.session.room.sender.SenderInfo.disambiguatedDisplayName] */
-    private fun resolveRoomMemberName(roomMemberSummary: RoomMemberSummaryEntity?,
-                                      roomMemberHelper: RoomMemberHelper): String? {
-        if (roomMemberSummary == null) return null
+    private fun resolveRoomMemberName(roomMemberSummary: RoomMemberSummaryEntity,
+                                      roomMemberHelper: RoomMemberHelper): String {
         val isUnique = roomMemberHelper.isUniqueDisplayName(roomMemberSummary.displayName)
         return if (isUnique) {
             roomMemberSummary.getBestName()
diff --git a/vector/src/main/java/im/vector/app/features/room/VectorRoomDisplayNameFallbackProvider.kt b/vector/src/main/java/im/vector/app/features/room/VectorRoomDisplayNameFallbackProvider.kt
index fe1d4e0f2f..33e63434ce 100644
--- a/vector/src/main/java/im/vector/app/features/room/VectorRoomDisplayNameFallbackProvider.kt
+++ b/vector/src/main/java/im/vector/app/features/room/VectorRoomDisplayNameFallbackProvider.kt
@@ -32,23 +32,32 @@ class VectorRoomDisplayNameFallbackProvider(
         return if (leftMemberNames.isEmpty()) {
             context.getString(R.string.room_displayname_empty_room)
         } else {
-            context.getString(R.string.room_displayname_empty_room_was, leftMemberNames.joinToString())
+            val was = when (val size = leftMemberNames.size) {
+                1    -> getNameFor1member(leftMemberNames[0])
+                2    -> getNameFor2members(leftMemberNames[0], leftMemberNames[1])
+                3    -> getNameFor3members(leftMemberNames[0], leftMemberNames[1], leftMemberNames[2])
+                4    -> getNameFor4members(leftMemberNames[0], leftMemberNames[1], leftMemberNames[2], leftMemberNames[3])
+                else -> getNameFor4membersAndMore(leftMemberNames[0], leftMemberNames[1], leftMemberNames[2], size - 3)
+            }
+            context.getString(R.string.room_displayname_empty_room_was, was)
         }
     }
 
-    override fun getNameFor2members(name1: String?, name2: String?): String {
+    override fun getNameFor1member(name: String) = name
+
+    override fun getNameFor2members(name1: String, name2: String): String {
         return context.getString(R.string.room_displayname_two_members, name1, name2)
     }
 
-    override fun getNameFor3members(name1: String?, name2: String?, name3: String?): String {
+    override fun getNameFor3members(name1: String, name2: String, name3: String): String {
         return context.getString(R.string.room_displayname_3_members, name1, name2, name3)
     }
 
-    override fun getNameFor4members(name1: String?, name2: String?, name3: String?, name4: String?): String {
+    override fun getNameFor4members(name1: String, name2: String, name3: String, name4: String): String {
         return context.getString(R.string.room_displayname_4_members, name1, name2, name3, name4)
     }
 
-    override fun getNameFor4membersAndMore(name1: String?, name2: String?, name3: String?, remainingCount: Int): String {
+    override fun getNameFor4membersAndMore(name1: String, name2: String, name3: String, remainingCount: Int): String {
         return context.resources.getQuantityString(
                 R.plurals.room_displayname_four_and_more_members,
                 remainingCount,