diff --git a/boot/at91dataflashboot/at91dataflashboot.mk b/boot/at91dataflashboot/at91dataflashboot.mk
index c66f27e343..cb329a90df 100644
--- a/boot/at91dataflashboot/at91dataflashboot.mk
+++ b/boot/at91dataflashboot/at91dataflashboot.mk
@@ -11,9 +11,14 @@ AT91DATAFLASHBOOT_SITE = ftp://www.at91.com/pub/buildroot
 AT91DATAFLASHBOOT_INSTALL_TARGET = NO
 AT91DATAFLASHBOOT_INSTALL_IMAGES = YES
 
+AT91DATAFLASHBOOT_CFLAGS = $(TARGET_CFLAGS) -fno-stack-protector
+ifeq ($(BR2_ARM_INSTRUCTIONS_THUMB),y)
+AT91DATAFLASHBOOT_CFLAGS += -marm
+endif
+
 define AT91DATAFLASHBOOT_BUILD_CMDS
 	make -C $(@D) CROSS_COMPILE=$(TARGET_CROSS) \
-		CFLAGS="$(TARGET_CFLAGS) -fno-stack-protector"
+		CFLAGS="$(AT91DATAFLASHBOOT_CFLAGS)"
 endef
 
 define AT91DATAFLASHBOOT_INSTALL_IMAGES_CMDS