diff --git a/core/embed/bootloader/bootui.c b/core/embed/bootloader/bootui.c
index 06061dff5a..1038252419 100644
--- a/core/embed/bootloader/bootui.c
+++ b/core/embed/bootloader/bootui.c
@@ -44,12 +44,20 @@
 
 #define BACKLIGHT_NORMAL 150
 
-#define COLOR_BL_BG COLOR_WHITE                   // background
-#define COLOR_BL_FG COLOR_BLACK                   // foreground
+#define COLOR_BL_BG COLOR_WHITE  // background
+#define COLOR_BL_FG COLOR_BLACK  // foreground
+
+#ifdef RGB16
 #define COLOR_BL_FAIL RGB16(0xFF, 0x00, 0x00)     // red
 #define COLOR_BL_DONE RGB16(0x00, 0xAE, 0x0B)     // green
 #define COLOR_BL_PROCESS RGB16(0x4A, 0x90, 0xE2)  // blue
 #define COLOR_BL_GRAY RGB16(0x99, 0x99, 0x99)     // gray
+#else
+#define COLOR_BL_FAIL COLOR_BL_FG
+#define COLOR_BL_DONE COLOR_BL_FG
+#define COLOR_BL_PROCESS COLOR_BL_FG
+#define COLOR_BL_GRAY COLOR_BL_FG
+#endif
 
 #define COLOR_WELCOME_BG COLOR_WHITE  // welcome background
 #define COLOR_WELCOME_FG COLOR_BLACK  // welcome foreground
@@ -84,7 +92,7 @@ void ui_screen_boot(const vendor_header *const vhdr,
                     const image_header *const hdr) {
   const int show_string = ((vhdr->vtrust & VTRUST_STRING) == 0);
   if ((vhdr->vtrust & VTRUST_RED) == 0) {
-    boot_background = RGB16(0xFF, 0x00, 0x00);  // red
+    boot_background = COLOR_BL_FAIL;
   } else {
     boot_background = COLOR_BLACK;
   }
diff --git a/core/embed/bootloader_ci/bootui.c b/core/embed/bootloader_ci/bootui.c
index 979cc87e7d..628aa4d424 100644
--- a/core/embed/bootloader_ci/bootui.c
+++ b/core/embed/bootloader_ci/bootui.c
@@ -30,11 +30,18 @@
 
 #define BACKLIGHT_NORMAL 150
 
-#define COLOR_BL_BG COLOR_WHITE                   // background
-#define COLOR_BL_FG COLOR_BLACK                   // foreground
+#define COLOR_BL_BG COLOR_WHITE  // background
+#define COLOR_BL_FG COLOR_BLACK  // foreground
+
+#ifdef RGB16
 #define COLOR_BL_FAIL RGB16(0xFF, 0x00, 0x00)     // red
 #define COLOR_BL_DONE RGB16(0x00, 0xAE, 0x0B)     // green
 #define COLOR_BL_PROCESS RGB16(0x4A, 0x90, 0xE2)  // blue
+#else
+#define COLOR_BL_FAIL COLOR_BL_FG
+#define COLOR_BL_DONE COLOR_BL_FG
+#define COLOR_BL_PROCESS COLOR_BL_FG
+#endif
 
 #define COLOR_WELCOME_BG COLOR_WHITE  // welcome background
 #define COLOR_WELCOME_FG COLOR_BLACK  // welcome foreground
diff --git a/core/embed/extmod/modtrezorui/display.h b/core/embed/extmod/modtrezorui/display.h
index aefff21414..c9969a7b39 100644
--- a/core/embed/extmod/modtrezorui/display.h
+++ b/core/embed/extmod/modtrezorui/display.h
@@ -55,7 +55,10 @@
 #define AVATAR_IMAGE_SIZE 144
 #define LOADER_ICON_SIZE 64
 
+#ifdef TREZOR_MODEL_T
 #define RGB16(R, G, B) ((R & 0xF8) << 8) | ((G & 0xFC) << 3) | ((B & 0xF8) >> 3)
+#endif
+
 #define COLOR_WHITE 0xFFFF
 #define COLOR_BLACK 0x0000
 
diff --git a/core/embed/trezorhal/common.c b/core/embed/trezorhal/common.c
index de6ac6f285..9b4a797dec 100644
--- a/core/embed/trezorhal/common.c
+++ b/core/embed/trezorhal/common.c
@@ -29,7 +29,11 @@
 
 #include "stm32f4xx_ll_utils.h"
 
+#ifdef RGB16
 #define COLOR_FATAL_ERROR RGB16(0x7F, 0x00, 0x00)
+#else
+#define COLOR_FATAL_ERROR COLOR_BLACK
+#endif
 
 // from util.s
 extern void shutdown_privileged(void);
diff --git a/core/embed/unix/common.c b/core/embed/unix/common.c
index 8538422a60..6b71b70579 100644
--- a/core/embed/unix/common.c
+++ b/core/embed/unix/common.c
@@ -32,7 +32,12 @@ void __shutdown(void) {
   main_clean_exit(3);
 }
 
+#ifdef RGB16
 #define COLOR_FATAL_ERROR RGB16(0x7F, 0x00, 0x00)
+#else
+// black on monochromatic displays
+#define COLOR_FATAL_ERROR 0x0000
+#endif
 
 void __attribute__((noreturn))
 __fatal_error(const char *expr, const char *msg, const char *file, int line,