diff --git a/app/src/main/java/com/geeksville/mesh/database/PacketRepository.kt b/app/src/main/java/com/geeksville/mesh/database/PacketRepository.kt
index 9775bb0db..7f0f54d9f 100644
--- a/app/src/main/java/com/geeksville/mesh/database/PacketRepository.kt
+++ b/app/src/main/java/com/geeksville/mesh/database/PacketRepository.kt
@@ -34,6 +34,10 @@ class PacketRepository @Inject constructor(private val packetDaoLazy: dagger.Laz
         packetDao.updateMessageStatus(d, m)
     }
 
+    suspend fun updateMessageId(d: DataPacket, id: Int) = withContext(Dispatchers.IO) {
+        packetDao.updateMessageId(d, id)
+    }
+
     suspend fun getDataPacketById(requestId: Int) = withContext(Dispatchers.IO) {
         packetDao.getDataPacketById(requestId)
     }
diff --git a/app/src/main/java/com/geeksville/mesh/database/dao/PacketDao.kt b/app/src/main/java/com/geeksville/mesh/database/dao/PacketDao.kt
index 9c166c024..979b699ea 100644
--- a/app/src/main/java/com/geeksville/mesh/database/dao/PacketDao.kt
+++ b/app/src/main/java/com/geeksville/mesh/database/dao/PacketDao.kt
@@ -48,6 +48,12 @@ interface PacketDao {
         findDataPacket(data)?.let { update(it.copy(data = new)) }
     }
 
+    @Transaction
+    fun updateMessageId(data: DataPacket, id: Int) {
+        val new = data.copy(id = id)
+        findDataPacket(data)?.let { update(it.copy(data = new)) }
+    }
+
     @Query("Select data from packet order by received_time asc")
     fun getDataPackets(): List<DataPacket>
 
diff --git a/app/src/main/java/com/geeksville/mesh/service/MeshService.kt b/app/src/main/java/com/geeksville/mesh/service/MeshService.kt
index e82f78083..d327586eb 100644
--- a/app/src/main/java/com/geeksville/mesh/service/MeshService.kt
+++ b/app/src/main/java/com/geeksville/mesh/service/MeshService.kt
@@ -850,6 +850,13 @@ class MeshService : Service(), Logging {
 
     private fun processQueuedPackets() = serviceScope.handledLaunch {
         packetRepository.get().getQueuedPackets()?.forEach { p ->
+            // check for duplicate packet IDs before sending (so ACK/NAK updates can work)
+            if (getDataPacketById(p.id)?.time != p.time) {
+                val newId = generatePacketId()
+                debug("Replaced duplicate packet ID in queue: ${p.id}, with: $newId")
+                packetRepository.get().updateMessageId(p, newId)
+                p.id = newId
+            }
             try {
                 sendNow(p)
             } catch (ex: Exception) {