diff --git a/hw/sun4m.c b/hw/sun4m.c
index 7756e5e0b0..b2d4cfa089 100644
--- a/hw/sun4m.c
+++ b/hw/sun4m.c
@@ -76,7 +76,7 @@
 #define KERNEL_LOAD_ADDR     0x00004000
 #define CMDLINE_ADDR         0x007ff000
 #define INITRD_LOAD_ADDR     0x00800000
-#define PROM_SIZE_MAX        (512 * 1024)
+#define PROM_SIZE_MAX        (1024 * 1024)
 #define PROM_VADDR           0xffd00000
 #define PROM_FILENAME        "openbios-sparc32"
 #define CFG_ADDR             0xd00000510ULL