diff --git a/lib/kiss/kiss_serial.rb b/lib/kiss/kiss_serial.rb
index c00411354760327a2d4a39519a4c7bf9e355dea6..39e1a5512fb6f25d4b2cd1768220ccbd21bb3930 100644
--- a/lib/kiss/kiss_serial.rb
+++ b/lib/kiss/kiss_serial.rb
@@ -41,6 +41,7 @@ module Kiss
 
         protected
         def write_interface(data)
+            data.map { |b| b.chr }.join
             puts 'write_interface:'
             p data
             @serial.write(data)