diff --git a/hw/application_fpga/Makefile b/hw/application_fpga/Makefile
index 3dafab6..1281b35 100644
--- a/hw/application_fpga/Makefile
+++ b/hw/application_fpga/Makefile
@@ -128,7 +128,9 @@ FIRMWARE_OBJS = \
 	$(P)/fw/tk1/assert.o \
 	$(P)/fw/tk1/led.o \
 	$(P)/fw/tk1/blake2s/blake2s.o \
-	$(P)/fw/tk1/syscall.o
+	$(P)/fw/tk1/syscall.o \
+	$(P)/fw/tk1/spi.o \
+	$(P)/fw/tk1/flash.o
 
 FIRMWARE_SOURCES = \
 	$(P)/fw/tk1/main.c \
@@ -137,7 +139,9 @@ FIRMWARE_SOURCES = \
 	$(P)/fw/tk1/assert.c \
 	$(P)/fw/tk1/led.c \
 	$(P)/fw/tk1/blake2s/blake2s.c \
-	$(P)/fw/tk1/syscall.c
+	$(P)/fw/tk1/syscall.c \
+	$(P)/fw/tk1/spi.c \
+	$(P)/fw/tk1/flash.c
 
 TESTFW_OBJS = \
 	$(P)/fw/testfw/main.o \
diff --git a/hw/application_fpga/fw/tk1/Makefile b/hw/application_fpga/fw/tk1/Makefile
index 3c1cd5f..2ac03fa 100644
--- a/hw/application_fpga/fw/tk1/Makefile
+++ b/hw/application_fpga/fw/tk1/Makefile
@@ -1,6 +1,6 @@
 # Uses ../.clang-format
 FMTFILES=main.c lib.h lib.c proto.h proto.c types.h assert.c assert.h led.c \
-	 led.h syscall.c
+	 led.h syscall.c spi.c spi.h flash.c flash.h
 .PHONY: fmt
 fmt:
 	clang-format --dry-run --ferror-limit=0 $(FMTFILES)
diff --git a/hw/application_fpga/fw/tk1/flash.c b/hw/application_fpga/fw/tk1/flash.c
index 3be9431..efa8c47 100644
--- a/hw/application_fpga/fw/tk1/flash.c
+++ b/hw/application_fpga/fw/tk1/flash.c
@@ -2,12 +2,11 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
 #include "flash.h"
+#include "../tk1/types.h"
 #include "../tk1_mem.h"
 #include "spi.h"
 
 #include <stdbool.h>
-#include <stddef.h>
-#include <stdint.h>
 
 // clang-format off
 static volatile uint32_t *timer			= (volatile uint32_t *)TK1_MMIO_TIMER_TIMER;
diff --git a/hw/application_fpga/fw/tk1/spi.c b/hw/application_fpga/fw/tk1/spi.c
index 4246ccb..ba50e35 100644
--- a/hw/application_fpga/fw/tk1/spi.c
+++ b/hw/application_fpga/fw/tk1/spi.c
@@ -2,11 +2,9 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
 #include "spi.h"
+#include "../tk1/types.h"
 #include "../tk1_mem.h"
 
-#include <stddef.h>
-#include <stdint.h>
-
 // clang-format off
 static volatile uint32_t *spi_en =         (volatile uint32_t *)(TK1_MMIO_TK1_BASE | 0x200);
 static volatile uint32_t *spi_xfer =       (volatile uint32_t *)(TK1_MMIO_TK1_BASE | 0x204);
@@ -64,7 +62,6 @@ static void _spi_read(uint8_t *buf, size_t size)
 	}
 }
 
-
 // Function to both read and write data to the connected SPI flash.
 int spi_transfer(uint8_t *cmd, size_t cmd_size, uint8_t *tx_buf, size_t tx_size,
 		 uint8_t *rx_buf, size_t rx_size)
diff --git a/hw/application_fpga/fw/tk1/spi.h b/hw/application_fpga/fw/tk1/spi.h
index 2c59f4c..0db6555 100644
--- a/hw/application_fpga/fw/tk1/spi.h
+++ b/hw/application_fpga/fw/tk1/spi.h
@@ -4,8 +4,7 @@
 #ifndef TKEY_SPI_H
 #define TKEY_SPI_H
 
-#include <stddef.h>
-#include <stdint.h>
+#include "../tk1/types.h"
 
 int spi_ready(void);
 int spi_transfer(uint8_t *cmd, size_t cmd_size, uint8_t *tx_buf, size_t tx_size,
diff --git a/hw/application_fpga/fw/tk1/types.h b/hw/application_fpga/fw/tk1/types.h
index 9a1fcff..2ed09d5 100644
--- a/hw/application_fpga/fw/tk1/types.h
+++ b/hw/application_fpga/fw/tk1/types.h
@@ -14,7 +14,7 @@ typedef long long int64_t;
 typedef unsigned char uint8_t;
 typedef unsigned long size_t;
 
-#define NULL ((char *)0)
+#define NULL ((void *)0)
 
 #define FALSE 0
 #define TRUE !FALSE