diff --git a/lib/logstash/codecs/json_lines.rb b/lib/logstash/codecs/json_lines.rb
index e0059c1..f3a4df1 100644
--- a/lib/logstash/codecs/json_lines.rb
+++ b/lib/logstash/codecs/json_lines.rb
@@ -57,6 +57,7 @@ class LogStash::Codecs::JSONLines < LogStash::Codecs::Base
 
   def register
     if @decode_size_limit_bytes == "none"
+      deprecation_logger.deprecated "`none` default value for `decode_size_limit_bytes` setting is going to be moved to a defined limit in a future version. Set a reasonable value compatible with your lines size."
       @buffer = FileWatch::BufferedTokenizer.new(@delimiter)
     else
       @buffer = FileWatch::BufferedTokenizer.new(@delimiter, @decode_size_limit_bytes.to_i)