diff --git a/app/src/main/java/com/vitorpamplona/amethyst/model/User.kt b/app/src/main/java/com/vitorpamplona/amethyst/model/User.kt
index df2c447dde..e62e50df0e 100644
--- a/app/src/main/java/com/vitorpamplona/amethyst/model/User.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/model/User.kt
@@ -86,7 +86,7 @@ class User(val pubkey: ByteArray) {
     @Synchronized
     fun getOrCreateChannel(user: User): MutableSet<Note> {
         return messages[user] ?: run {
-            val channel = mutableSetOf<Note>()
+            val channel = Collections.synchronizedSet(mutableSetOf<Note>())
             messages[user] = channel
             channel
         }
@@ -137,6 +137,14 @@ class User(val pubkey: ByteArray) {
         }
     }
 
+    fun hasSentMessagesTo(user: User?): Boolean {
+        val messagesToUser = messages[user] ?: return false
+
+        return synchronized(messagesToUser) {
+            messagesToUser.firstOrNull { this == it.author } != null
+        }
+    }
+
     // Model Observers
     private var listeners = setOf<Listener>()
 
diff --git a/app/src/main/java/com/vitorpamplona/amethyst/service/NostrChatRoomDataSource.kt b/app/src/main/java/com/vitorpamplona/amethyst/service/NostrChatRoomDataSource.kt
index ed761f0692..35a6742261 100644
--- a/app/src/main/java/com/vitorpamplona/amethyst/service/NostrChatRoomDataSource.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/service/NostrChatRoomDataSource.kt
@@ -33,9 +33,13 @@ object NostrChatRoomDataSource: NostrDataSource<Note>("ChatroomFeed") {
 
   // returns the last Note of each user.
   override fun feed(): List<Note> {
-    val messages = account.userProfile().messages[withUser]?.filter { account.isAcceptable(it) }
+    val messages = account.userProfile().messages[withUser] ?: return emptyList()
 
-    return messages?.sortedBy { it.event?.createdAt }?.reversed() ?: emptyList()
+    val filteredMessages = synchronized(messages) {
+      messages.filter { account.isAcceptable(it) }
+    }
+
+    return filteredMessages.sortedBy { it.event?.createdAt }.reversed()
   }
 
   override fun updateChannelFilters() {
diff --git a/app/src/main/java/com/vitorpamplona/amethyst/service/NostrChatroomListDataSource.kt b/app/src/main/java/com/vitorpamplona/amethyst/service/NostrChatroomListDataSource.kt
index 3e2dd8a14b..ddf8536dfd 100644
--- a/app/src/main/java/com/vitorpamplona/amethyst/service/NostrChatroomListDataSource.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/service/NostrChatroomListDataSource.kt
@@ -67,19 +67,20 @@ object NostrChatroomListDataSource: NostrDataSource<Note>("MailBoxFeed") {
     val messagingWith = messages.keys().toList().filter { account.isAcceptable(it) }
 
     val privateMessages = messagingWith.mapNotNull {
-      messages[it]?.sortedBy { it.event?.createdAt }?.lastOrNull { it.event != null }
+      val conversation = messages[it]
+      if (conversation != null) {
+        synchronized(conversation) {
+          conversation.sortedBy { it.event?.createdAt }.lastOrNull { it.event != null }
+        }
+      } else {
+        null
+      }
     }
 
     val publicChannels = account.followingChannels().map {
       it.notes.values.filter { account.isAcceptable(it) }.sortedBy { it.event?.createdAt }.lastOrNull { it.event != null }
     }
 
-    val channelsCreatedByMe = LocalCache.channels.values.filter {
-      it.creator == account.userProfile()
-    }.map {
-      it.notes.values.sortedBy { it.event?.createdAt }.lastOrNull { it.event != null }
-    }
-
     return (privateMessages + publicChannels).filterNotNull().sortedBy { it.event?.createdAt }.reversed()
   }
 
diff --git a/app/src/main/java/com/vitorpamplona/amethyst/ui/navigation/Routes.kt b/app/src/main/java/com/vitorpamplona/amethyst/ui/navigation/Routes.kt
index 07a944de5c..be0cd61dcf 100644
--- a/app/src/main/java/com/vitorpamplona/amethyst/ui/navigation/Routes.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/ui/navigation/Routes.kt
@@ -138,7 +138,7 @@ private fun messagesHasNewItems(cache: NotificationCache): Boolean {
     return NostrChatroomListDataSource.feed().take(100).filter {
         // only for known sources
         val me = NostrChatroomListDataSource.account.userProfile()
-        it.channel != null || me.messages[it.author]?.firstOrNull { me == it.author } != null
+        it.channel != null || me.hasSentMessagesTo(it.author)
     }.filter {
         val lastTime = if (it.channel != null) {
             cache.load("Channel/${it.channel!!.idHex}", context)
diff --git a/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/FeedViewModel.kt b/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/FeedViewModel.kt
index ef0855f21b..f12bc2805e 100644
--- a/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/FeedViewModel.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/FeedViewModel.kt
@@ -39,7 +39,7 @@ class NostrChatroomListKnownFeedViewModel: FeedViewModel(NostrChatroomListDataSo
         // Filter: all channels + PMs the account has replied to
         return super.newListFromDataSource().filter {
             val me = NostrChatroomListDataSource.account.userProfile()
-            it.channel != null || me.messages[it.author]?.firstOrNull { me == it.author } != null
+            it.channel != null || me.hasSentMessagesTo(it.author)
         }
     }
 }
@@ -48,7 +48,7 @@ class NostrChatroomListNewFeedViewModel: FeedViewModel(NostrChatroomListDataSour
         // Filter: no channels + PMs the account has never replied to
         return super.newListFromDataSource().filter {
             val me = NostrChatroomListDataSource.account.userProfile()
-            it.channel == null && me.messages[it.author]?.firstOrNull { me == it.author } == null
+            it.channel == null && !me.hasSentMessagesTo(it.author)
         }
     }
 }