diff --git a/core/embed/sys/mpu/stm32f4/mpu.c b/core/embed/sys/mpu/stm32f4/mpu.c
index 6632bcc3d1..dd1e2cb5a1 100644
--- a/core/embed/sys/mpu/stm32f4/mpu.c
+++ b/core/embed/sys/mpu/stm32f4/mpu.c
@@ -96,7 +96,7 @@ static inline void mpu_enable(void) {
 static void mpu_init_fixed_regions(void) {
   // Regions #0 to #4 are fixed for all targets
 
-#ifdef BOARDLOADER
+#if defined(BOARDLOADER)
   // clang-format off
   // Code in the Flash Bank #1 (Unprivileged, Read-Only, Executable)
   // Subregion: 48KB = 64KB except 2/8 at end
@@ -113,8 +113,7 @@ static void mpu_init_fixed_regions(void) {
   // Subregion:  192KB = 256KB except 2/8 at end
   SET_REGION( 4, SRAM_BASE,             SIZE_256KB, 0xC0, SRAM,       FULL_ACCESS );
   // clang-format on
-#endif
-#ifdef BOOTLOADER
+#elif defined(BOOTLOADER)
   // clang-format off
   // Bootloader code in the Flash Bank #1 (Unprivileged, Read-Only, Executable)
   // Subregion: 128KB = 1024KB except 2/8 at start
@@ -131,8 +130,7 @@ static void mpu_init_fixed_regions(void) {
   // Subregion:  192KB = 256KB except 2/8 at end
   SET_REGION( 4, SRAM_BASE,             SIZE_256KB, 0xC0, SRAM,       FULL_ACCESS );
   // clang-format on
-#endif
-#ifdef KERNEL
+#elif defined(KERNEL)
   // clang-format off
   // Code in the Flash Bank #1 (Unprivileged, Read-Only, Executable)
   // Subregion: 768KB = 1024KB except 2/8 at start
@@ -149,8 +147,7 @@ static void mpu_init_fixed_regions(void) {
   // SubRegion: 8KB at the beginning + 16KB at the end of 64KB CCMRAM
   SET_REGION( 4, CCMDATARAM_BASE,       SIZE_64KB,  0x3E, SRAM,       PRIV_RW );
   // clang-format on
-#endif
-#ifdef FIRMWARE
+#elif defined(FIRMWARE)
   // clang-format off
   // Code in the Flash Bank #1 (Unprivileged, Read-Only, Executable)
   // Subregion: 768KB = 1024KB except 2/8 at start
@@ -165,8 +162,7 @@ static void mpu_init_fixed_regions(void) {
   SET_REGION( 3, SRAM_BASE,             SIZE_256KB, 0xC0, SRAM,       FULL_ACCESS );
   DIS_REGION( 4 );
   // clang-format on
-#endif
-#ifdef TREZOR_PRODTEST
+#elif defined(TREZOR_PRODTEST)
   // clang-format off
   // Code in the Flash Bank #1 (Unprivileged, Read-Only, Executable)
   // Subregion: 768KB = 1024KB except 2/8 at start
@@ -183,6 +179,8 @@ static void mpu_init_fixed_regions(void) {
   // (used in production test to invalidate the firmware)
   SET_REGION( 4, FIRMWARE_START,        SIZE_1KB,   0x00, FLASH_DATA, PRIV_RW_URO );
   // clang-format on
+#else
+#error "Unknown build target"
 #endif
 
   // Regions #5 to #7 are banked
diff --git a/core/embed/sys/mpu/stm32u5/mpu.c b/core/embed/sys/mpu/stm32u5/mpu.c
index 1f61e62169..d58f4be647 100644
--- a/core/embed/sys/mpu/stm32u5/mpu.c
+++ b/core/embed/sys/mpu/stm32u5/mpu.c
@@ -203,16 +203,14 @@ static void mpu_init_fixed_regions(void) {
   SET_REGION( 2, BOOTLOADER_START,         BOOTLOADER_MAXSIZE,  FLASH_DATA,  YES,    NO );
   SET_REGION( 3, FIRMWARE_START,           FIRMWARE_MAXSIZE,    FLASH_DATA,  YES,    NO );
   SET_REGION( 4, AUX1_RAM_START,           AUX1_RAM_SIZE,       SRAM,        YES,    NO );
-#endif
-#if defined(BOOTLOADER)
+#elif defined(BOOTLOADER)
   //   REGION    ADDRESS                   SIZE                TYPE       WRITE   UNPRIV
   SET_REGION( 0, BOOTLOADER_START,         BOOTLOADER_MAXSIZE, FLASH_CODE,   NO,    NO );
   SET_REGION( 1, MAIN_RAM_START,           MAIN_RAM_SIZE,      SRAM,        YES,    NO );
   SET_REGION( 2, FIRMWARE_START,           FIRMWARE_MAXSIZE,   FLASH_DATA,  YES,    NO );
   DIS_REGION( 3 );
   SET_REGION( 4, AUX1_RAM_START,           AUX1_RAM_SIZE ,     SRAM,        YES,    NO );
-#endif
-#if defined(KERNEL)
+#elif defined(KERNEL)
   //   REGION    ADDRESS                   SIZE                TYPE       WRITE   UNPRIV
   SET_REGRUN( 0, KERNEL_FLASH_START,       KERNEL_FLASH_SIZE,  FLASH_CODE,   NO,    NO ); // Kernel Code
   SET_REGION( 1, MAIN_RAM_START,           MAIN_RAM_SIZE,      SRAM,        YES,    NO ); // Kernel RAM
@@ -223,21 +221,22 @@ static void mpu_init_fixed_regions(void) {
 #else
   DIS_REGION( 4 );
 #endif
-#endif
-#if defined(FIRMWARE)
+
+#elif defined(FIRMWARE)
   //   REGION    ADDRESS                   SIZE                TYPE       WRITE   UNPRIV
   SET_REGION( 0, FIRMWARE_START,           FIRMWARE_MAXSIZE,   FLASH_CODE,   NO,    NO );
   SET_REGION( 1, MAIN_RAM_START,           MAIN_RAM_SIZE,      SRAM,        YES,    NO );
   DIS_REGION( 2 );
   DIS_REGION( 3 );
   SET_REGION( 4, AUX1_RAM_START,           AUX1_RAM_SIZE,      SRAM,        YES,    NO );
-#endif
-#if defined(TREZOR_PRODTEST)
+#elif defined(TREZOR_PRODTEST)
   SET_REGION( 0, FIRMWARE_START,           1024,               FLASH_DATA,  YES,    NO );
   SET_REGION( 1, FIRMWARE_START + 1024,    FIRMWARE_MAXSIZE - 1024, FLASH_CODE,   NO,    NO );
   SET_REGION( 2, MAIN_RAM_START,           MAIN_RAM_SIZE,     SRAM,        YES,    NO );
   DIS_REGION( 3 );
   SET_REGION( 4, AUX1_RAM_START,           AUX1_RAM_SIZE,     SRAM,        YES,    NO );
+#else
+  #error "Unknown build target"
 #endif
 
   // Regions #5 to #7 are banked