diff --git a/app/models/conversation.rb b/app/models/conversation.rb
index b175961c1..80b930493 100644
--- a/app/models/conversation.rb
+++ b/app/models/conversation.rb
@@ -166,11 +166,11 @@ class Conversation < ApplicationRecord
   end
 
   def unread_messages
-    messages.created_since(agent_last_seen_at)
+    agent_last_seen_at.present? ? messages.created_since(agent_last_seen_at) : messages
   end
 
   def unread_incoming_messages
-    messages.incoming.created_since(agent_last_seen_at)
+    unread_messages.incoming
   end
 
   def push_event_data
diff --git a/spec/models/conversation_spec.rb b/spec/models/conversation_spec.rb
index db50ebe50..a7bc919b3 100644
--- a/spec/models/conversation_spec.rb
+++ b/spec/models/conversation_spec.rb
@@ -497,6 +497,12 @@ RSpec.describe Conversation do
     it 'returns unread incoming messages' do
       expect(unread_incoming_messages).to contain_exactly(message)
     end
+
+    it 'returns unread incoming messages even if the agent has not seen the conversation' do
+      conversation.update!(agent_last_seen_at: nil)
+
+      expect(unread_incoming_messages).to contain_exactly(message)
+    end
   end
 
   describe '#push_event_data' do