diff --git a/emulator/setup.c b/emulator/setup.c
index f994916d3..2ea8f9219 100644
--- a/emulator/setup.c
+++ b/emulator/setup.c
@@ -48,6 +48,10 @@ void setup(void) {
 	setup_flash();
 }
 
+void __attribute__((noreturn)) shutdown(void) {
+	for(;;);
+}
+
 void emulatorRandom(void *buffer, size_t size) {
 	ssize_t n = read(urandom, buffer, size);
 	if (n < 0 || ((size_t) n) != size) {
diff --git a/firmware/bl_check.c b/firmware/bl_check.c
index 1e53497f2..0d6b3bba0 100644
--- a/firmware/bl_check.c
+++ b/firmware/bl_check.c
@@ -47,7 +47,7 @@ void check_bootloader(void)
 
 	if (!known_bootloader(r, hash)) {
 		layoutDialog(&bmp_icon_error, NULL, NULL, NULL, "Unknown bootloader", "detected.", NULL, "Unplug your TREZOR", "contact our support.", NULL);
-		system_halt();
+		shutdown();
 	}
 
 	if (r == 32 && 0 == memcmp(hash, bl_hash, 32)) {
@@ -55,6 +55,11 @@ void check_bootloader(void)
 		return;
 	}
 
+#if 0
+	// ENABLE THIS AT YOUR OWN RISK
+	// ATTEMPTING TO OVERWRITE BOOTLOADER WITH UNSIGNED FIRMWARE MAY BRICK
+	// YOUR DEVICE.
+
 	// unlock sectors
 	memory_write_unlock();
 
@@ -71,5 +76,6 @@ void check_bootloader(void)
 
 	// show info and halt
 	layoutDialog(&bmp_icon_info, NULL, NULL, NULL, _("Update finished"), _("successfully."), NULL, _("Please reconnect"), _("the device."), NULL);
-	system_halt();
+	shutdown();
+#endif
 }
diff --git a/script/cibuild b/script/cibuild
index 023969661..b8dc11226 100755
--- a/script/cibuild
+++ b/script/cibuild
@@ -19,6 +19,7 @@ if [ "$FASTFLASH" = 1 ]; then
     make -C fastflash
 fi
 
+make -C bootloader
 make -C vendor/nanopb/generator/proto
 make -C firmware/protob
 
diff --git a/util.h b/util.h
index 04fb637c2..8b6a9f2eb 100644
--- a/util.h
+++ b/util.h
@@ -43,13 +43,14 @@ void data2hex(const void *data, uint32_t len, char *str);
 // read protobuf integer and advance pointer
 uint32_t readprotobufint(uint8_t **ptr);
 
+extern void __attribute__((noreturn)) shutdown(void);
+
 #if !EMULATOR
 // defined in memory.ld
 extern uint8_t _ram_start[], _ram_end[];
 
 // defined in startup.s
 extern void memset_reg(void *start, void *stop, uint32_t val);
-extern void __attribute__((noreturn)) shutdown(void);
 
 #define FW_SIGNED       0x5A3CA5C3
 #define FW_UNTRUSTED    0x00000000