diff --git a/hw/sun4m.c b/hw/sun4m.c
index a7456b92f8132e0390c824099517c6a3fde47fd2..fcd0ace5e803079fcc22714bf9fbcc2d2b2615b9 100644
--- a/hw/sun4m.c
+++ b/hw/sun4m.c
@@ -80,6 +80,7 @@
 #define PROM_VADDR           0xffd00000
 #define PROM_FILENAME        "openbios-sparc32"
 #define CFG_ADDR             0xd00000510ULL
+#define FW_CFG_SUN4M_DEPTH   (FW_CFG_ARCH_LOCAL + 0x00)
 
 // Control plane, 8-bit and 24-bit planes
 #define TCX_SIZE             (9 * 1024 * 1024)
@@ -582,6 +583,7 @@ static void sun4m_hw_init(const struct hwdef *hwdef, ram_addr_t RAM_size,
     fw_cfg_add_i32(fw_cfg, FW_CFG_ID, 1);
     fw_cfg_add_i64(fw_cfg, FW_CFG_RAM_SIZE, (uint64_t)ram_size);
     fw_cfg_add_i16(fw_cfg, FW_CFG_MACHINE_ID, hwdef->machine_id);
+    fw_cfg_add_i16(fw_cfg, FW_CFG_SUN4M_DEPTH, graphic_depth);
 }
 
 static void sun4c_hw_init(const struct hwdef *hwdef, ram_addr_t RAM_size,