diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/RoomMember.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/RoomMember.kt
index e28ba90b52..6a4d8e3c94 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/RoomMember.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/room/model/RoomMember.kt
@@ -26,7 +26,7 @@ import im.vector.matrix.android.api.session.events.model.UnsignedData
 @JsonClass(generateAdapter = true)
 data class RoomMember(
         @Json(name = "membership") val membership: Membership,
-        @Json(name = "reason") val reason: String?,
+        @Json(name = "reason") val reason: String? = null,
         @Json(name = "displayname") val displayName: String? = null,
         @Json(name = "avatar_url") val avatarUrl: String? = null,
         @Json(name = "is_direct") val isDirect: Boolean = false,