diff --git a/matrix-sdk-android-rx/src/main/java/im/vector/matrix/rx/RxSession.kt b/matrix-sdk-android-rx/src/main/java/im/vector/matrix/rx/RxSession.kt
index 82e1d71f44..87ff6f0390 100644
--- a/matrix-sdk-android-rx/src/main/java/im/vector/matrix/rx/RxSession.kt
+++ b/matrix-sdk-android-rx/src/main/java/im/vector/matrix/rx/RxSession.kt
@@ -95,10 +95,10 @@ class RxSession(private val session: Session) {
         session.searchUsersDirectory(search, limit, excludedUserIds, it)
     }
 
-    fun joinRoom(roomId: String,
+    fun joinRoom(roomIdOrAlias: String,
                  reason: String? = null,
                  viaServers: List<String> = emptyList()): Single<Unit> = singleBuilder {
-        session.joinRoom(roomId, reason, viaServers, it)
+        session.joinRoom(roomIdOrAlias, reason, viaServers, it)
     }
 
     fun getRoomIdByAlias(roomAlias: String,
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/RoomDirectoryService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/RoomDirectoryService.kt
index c0e413f83b..0273c789dd 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/RoomDirectoryService.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/RoomDirectoryService.kt
@@ -35,9 +35,9 @@ interface RoomDirectoryService {
                        callback: MatrixCallback<PublicRoomsResponse>): Cancelable
 
     /**
-     * Join a room by id
+     * Join a room by id, or room alias
      */
-    fun joinRoom(roomId: String,
+    fun joinRoom(roomIdOrAlias: String,
                  reason: String? = null,
                  callback: MatrixCallback<Unit>): Cancelable
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/RoomService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/RoomService.kt
index 9fec605bd9..93761dfd26 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/RoomService.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/RoomService.kt
@@ -36,11 +36,11 @@ interface RoomService {
 
     /**
      * Join a room by id
-     * @param roomId the roomId of the room to join
+     * @param roomIdOrAlias the roomId or the room alias of the room to join
      * @param reason optional reason for joining the room
      * @param viaServers the servers to attempt to join the room through. One of the servers must be participating in the room.
      */
-    fun joinRoom(roomId: String,
+    fun joinRoom(roomIdOrAlias: String,
                  reason: String? = null,
                  viaServers: List<String> = emptyList(),
                  callback: MatrixCallback<Unit>): Cancelable
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/create/CreateRoomResponse.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/create/CreateRoomResponse.kt
index c437bcfbf1..29c8cb830d 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/create/CreateRoomResponse.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/create/CreateRoomResponse.kt
@@ -21,5 +21,10 @@ import com.squareup.moshi.JsonClass
 
 @JsonClass(generateAdapter = true)
 internal data class CreateRoomResponse(
-        @Json(name = "room_id") var roomId: String? = null
+        /**
+         * Required. The created room's ID.
+         */
+        @Json(name = "room_id") var roomId: String
 )
+
+internal typealias JoinRoomResponse = CreateRoomResponse
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/DefaultRoomDirectoryService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/DefaultRoomDirectoryService.kt
index 711e2bd97c..ef55702de6 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/DefaultRoomDirectoryService.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/DefaultRoomDirectoryService.kt
@@ -44,9 +44,9 @@ internal class DefaultRoomDirectoryService @Inject constructor(private val getPu
                 .executeBy(taskExecutor)
     }
 
-    override fun joinRoom(roomId: String, reason: String?, callback: MatrixCallback<Unit>): Cancelable {
+    override fun joinRoom(roomIdOrAlias: String, reason: String?, callback: MatrixCallback<Unit>): Cancelable {
         return joinRoomTask
-                .configureWith(JoinRoomTask.Params(roomId, reason)) {
+                .configureWith(JoinRoomTask.Params(roomIdOrAlias, reason)) {
                     this.callback = callback
                 }
                 .executeBy(taskExecutor)
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/DefaultRoomService.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/DefaultRoomService.kt
index e049c1869d..84fc357160 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/DefaultRoomService.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/DefaultRoomService.kt
@@ -139,9 +139,9 @@ internal class DefaultRoomService @Inject constructor(
                 .executeBy(taskExecutor)
     }
 
-    override fun joinRoom(roomId: String, reason: String?, viaServers: List<String>, callback: MatrixCallback<Unit>): Cancelable {
+    override fun joinRoom(roomIdOrAlias: String, reason: String?, viaServers: List<String>, callback: MatrixCallback<Unit>): Cancelable {
         return joinRoomTask
-                .configureWith(JoinRoomTask.Params(roomId, reason, viaServers)) {
+                .configureWith(JoinRoomTask.Params(roomIdOrAlias, reason, viaServers)) {
                     this.callback = callback
                 }
                 .executeBy(taskExecutor)
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/RoomAPI.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/RoomAPI.kt
index 9be63565fe..f5ddf6ae4b 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/RoomAPI.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/RoomAPI.kt
@@ -20,6 +20,7 @@ import im.vector.matrix.android.api.session.events.model.Content
 import im.vector.matrix.android.api.session.events.model.Event
 import im.vector.matrix.android.api.session.room.model.create.CreateRoomParams
 import im.vector.matrix.android.api.session.room.model.create.CreateRoomResponse
+import im.vector.matrix.android.api.session.room.model.create.JoinRoomResponse
 import im.vector.matrix.android.api.session.room.model.roomdirectory.PublicRoomsParams
 import im.vector.matrix.android.api.session.room.model.roomdirectory.PublicRoomsResponse
 import im.vector.matrix.android.api.session.room.model.thirdparty.ThirdPartyProtocol
@@ -223,13 +224,13 @@ internal interface RoomAPI {
      * Join the given room.
      *
      * @param roomIdOrAlias the room id or alias
-     * @param server_name the servers to attempt to join the room through
+     * @param viaServers the servers to attempt to join the room through
      * @param params the request body
      */
     @POST(NetworkConstants.URI_API_PREFIX_PATH_R0 + "join/{roomIdOrAlias}")
     fun join(@Path("roomIdOrAlias") roomIdOrAlias: String,
              @Query("server_name") viaServers: List<String>,
-             @Body params: Map<String, String?>): Call<Unit>
+             @Body params: Map<String, String?>): Call<JoinRoomResponse>
 
     /**
      * Leave the given room.
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/create/CreateRoomTask.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/create/CreateRoomTask.kt
index f120130739..7314f55961 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/create/CreateRoomTask.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/create/CreateRoomTask.kt
@@ -66,7 +66,7 @@ internal class DefaultCreateRoomTask @Inject constructor(
         val createRoomResponse = executeRequest<CreateRoomResponse>(eventBus) {
             apiCall = roomAPI.createRoom(createRoomParams)
         }
-        val roomId = createRoomResponse.roomId!!
+        val roomId = createRoomResponse.roomId
         // Wait for room to come back from the sync (but it can maybe be in the DB if the sync response is received before)
         try {
             awaitNotEmptyResult(realmConfiguration, TimeUnit.MINUTES.toMillis(1L)) { realm ->
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/membership/joining/JoinRoomTask.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/membership/joining/JoinRoomTask.kt
index 0153930226..635f3955c2 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/membership/joining/JoinRoomTask.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/membership/joining/JoinRoomTask.kt
@@ -17,6 +17,7 @@
 package im.vector.matrix.android.internal.session.room.membership.joining
 
 import im.vector.matrix.android.api.session.room.failure.JoinRoomFailure
+import im.vector.matrix.android.api.session.room.model.create.JoinRoomResponse
 import im.vector.matrix.android.internal.database.awaitNotEmptyResult
 import im.vector.matrix.android.internal.database.model.RoomEntity
 import im.vector.matrix.android.internal.database.model.RoomEntityFields
@@ -33,7 +34,7 @@ import javax.inject.Inject
 
 internal interface JoinRoomTask : Task<JoinRoomTask.Params, Unit> {
     data class Params(
-            val roomId: String,
+            val roomIdOrAlias: String,
             val reason: String?,
             val viaServers: List<String> = emptyList()
     )
@@ -48,19 +49,20 @@ internal class DefaultJoinRoomTask @Inject constructor(
 ) : JoinRoomTask {
 
     override suspend fun execute(params: JoinRoomTask.Params) {
-        executeRequest<Unit>(eventBus) {
-            apiCall = roomAPI.join(params.roomId, params.viaServers, mapOf("reason" to params.reason))
+        val joinRoomResponse = executeRequest<JoinRoomResponse>(eventBus) {
+            apiCall = roomAPI.join(params.roomIdOrAlias, params.viaServers, mapOf("reason" to params.reason))
         }
         // Wait for room to come back from the sync (but it can maybe be in the DB is the sync response is received before)
+        val roomId = joinRoomResponse.roomId
         try {
             awaitNotEmptyResult(realmConfiguration, TimeUnit.MINUTES.toMillis(1L)) { realm ->
                 realm.where(RoomEntity::class.java)
-                        .equalTo(RoomEntityFields.ROOM_ID, params.roomId)
+                        .equalTo(RoomEntityFields.ROOM_ID, roomId)
             }
         } catch (exception: TimeoutCancellationException) {
             throw JoinRoomFailure.JoinedWithTimeout
         }
-        setReadMarkers(params.roomId)
+        setReadMarkers(roomId)
     }
 
     private suspend fun setReadMarkers(roomId: String) {