diff --git a/lib/logstash/inputs/cloudwatch_logs.rb b/lib/logstash/inputs/cloudwatch_logs.rb
index c3ca546..ddeb59c 100644
--- a/lib/logstash/inputs/cloudwatch_logs.rb
+++ b/lib/logstash/inputs/cloudwatch_logs.rb
@@ -173,8 +173,6 @@ def map_group_to_log_type(group)
       'opensearch'
     when %r{/aws/ElasticCache/.*}i
       'elasticache'
-    else
-      'unknown log type'
     end
   end
 
@@ -248,7 +246,7 @@ def process_log(log, group, log_type)
       event.set('[cloudwatch_logs][log_stream]', log.log_stream_name)
       event.set('[cloudwatch_logs][event_id]', log.event_id)
       event.set('[cloudwatch_logs][tags]', tags)
-      event.set('[cloudwatch_logs][log_type]', log_type)
+      event.set('[cloudwatch_logs][log_type]', log_type) unless log_type.nil?
       decorate(event)
 
       @queue << event