diff --git a/lib/kiss/kiss_serial.rb b/lib/kiss/kiss_serial.rb
index 077a862f75274df311837dc2c9f0de391aeeb975..c00411354760327a2d4a39519a4c7bf9e355dea6 100644
--- a/lib/kiss/kiss_serial.rb
+++ b/lib/kiss/kiss_serial.rb
@@ -30,9 +30,9 @@ module Kiss
         protected
         def read_interface
             read_data = @serial.read(@read_bytes)
-            puts 'read_interface:'
-            p read_data
             if read_data
+                puts 'read_interface:'
+                p read_data
                 return read_data.chars.map { |c| c.ord }
             else
                 return nil