diff --git a/src/atsamd/Kconfig b/src/atsamd/Kconfig
index 991e0376..2d08b179 100644
--- a/src/atsamd/Kconfig
+++ b/src/atsamd/Kconfig
@@ -14,6 +14,7 @@ config ATSAMD_SELECT
     select HAVE_CHIPID
     select HAVE_STEPPER_OPTIMIZED_BOTH_EDGE
     select HAVE_BOOTLOADER_REQUEST
+    select HAVE_LIMITED_CODE_SIZE if FLASH_SIZE < 0x10000
 
 config HAVE_SERCOM
     depends on HAVE_GPIO_I2C || HAVE_GPIO_SPI
diff --git a/src/atsamd/Makefile b/src/atsamd/Makefile
index 2416200f..c79c0a93 100644
--- a/src/atsamd/Makefile
+++ b/src/atsamd/Makefile
@@ -7,6 +7,7 @@ dirs-y += src/atsamd src/generic lib/fast-hash
 
 MCU := $(shell echo $(CONFIG_MCU) | tr a-z A-Z)
 
+CFLAGS-$(CONFIG_HAVE_LIMITED_CODE_SIZE) += -Os
 CFLAGS-$(CONFIG_MACH_SAMC21) += -mcpu=cortex-m0plus -Ilib/samc21/samc21/include
 CFLAGS-$(CONFIG_MACH_SAMD21) += -mcpu=cortex-m0plus -Ilib/samd21/samd21a/include
 CFLAGS-$(CONFIG_MACH_SAMD51) += -Ilib/samd51/samd51a/include