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..3f440a7d7b 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 +26,15 @@ class TestRoomDisplayNameFallbackProvider : RoomDisplayNameFallbackProvider {
     override fun getNameForEmptyRoom(isDirect: Boolean, leftMemberNames: List<String>) =
             "Empty room"
 
-    override fun getNameFor2members(name1: String?, name2: String?) =
+    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..6028bc837d 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 +19,8 @@ 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 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..219ef694a4 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
@@ -149,9 +149,8 @@ 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..57257dd597 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
@@ -36,19 +36,19 @@ class VectorRoomDisplayNameFallbackProvider(
         }
     }
 
-    override fun getNameFor2members(name1: String?, name2: String?): String {
+    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,