diff --git a/hardware/arduino/boards.txt b/hardware/arduino/boards.txt
index 0ae40d3b6..c252a758d 100644
--- a/hardware/arduino/boards.txt
+++ b/hardware/arduino/boards.txt
@@ -10,7 +10,7 @@ uno.bootloader.extended_fuses=0x05
 uno.bootloader.path=optiboot
 uno.bootloader.file=optiboot_atmega328.hex
 uno.bootloader.unlock_bits=0x3F
-uno.bootloader.lock_bits=0x0F
+uno.bootloader.lock_bits=0x2F
 uno.build.mcu=atmega328p
 uno.build.f_cpu=16000000L
 uno.build.core=arduino