Logstash JSON codec fails to parse special characters

Not sure if I'm missing something here...

I'm loading JSON into logstash using the Kafka input plugin with the JSON codec.

I'm getting errors only when my input includes unicode characters (like ≤).

JSON parse error, original data now in message field {:message=>"Unexpected end-of-input: was expecting closing quote for a string value

It appears like it's dropping the escape character for the final quote for my JSON string.

My source data is correct going into Kafka, encoded in UTF-8 (as all JSON data should be). The codec is similarly configured with UTF-8, which is also the default.

Any ideas?