diff --git a/hw/ppc/mac_newworld.c b/hw/ppc/mac_newworld.c
index 4bdaa8d398..e493dc1b4b 100644
--- a/hw/ppc/mac_newworld.c
+++ b/hw/ppc/mac_newworld.c
@@ -72,6 +72,8 @@
 #define MAX_IDE_BUS 2
 #define CFG_ADDR 0xf0000510
 #define TBFREQ (100UL * 1000UL * 1000UL)
+#define CLOCKFREQ (266UL * 1000UL * 1000UL)
+#define BUSFREQ (100UL * 1000UL * 1000UL)
 
 /* debug UniNorth */
 //#define DEBUG_UNIN
@@ -467,7 +469,8 @@ static void ppc_core99_init(MachineState *machine)
         fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_TBFREQ, TBFREQ);
     }
     /* Mac OS X requires a "known good" clock-frequency value; pass it one. */
-    fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_CLOCKFREQ, 266000000);
+    fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_CLOCKFREQ, CLOCKFREQ);
+    fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_BUSFREQ, BUSFREQ);
 
     qemu_register_boot_set(fw_cfg_boot_set, fw_cfg);
 }
diff --git a/hw/ppc/mac_oldworld.c b/hw/ppc/mac_oldworld.c
index 77598e44cc..4b5e905fc2 100644
--- a/hw/ppc/mac_oldworld.c
+++ b/hw/ppc/mac_oldworld.c
@@ -46,6 +46,8 @@
 #define MAX_IDE_BUS 2
 #define CFG_ADDR 0xf0000510
 #define TBFREQ 16600000UL
+#define CLOCKFREQ 266000000UL
+#define BUSFREQ 66000000UL
 
 static int fw_cfg_boot_set(void *opaque, const char *boot_device)
 {
@@ -337,7 +339,8 @@ static void ppc_heathrow_init(MachineState *machine)
         fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_TBFREQ, TBFREQ);
     }
     /* Mac OS X requires a "known good" clock-frequency value; pass it one. */
-    fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_CLOCKFREQ, 266000000);
+    fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_CLOCKFREQ, CLOCKFREQ);
+    fw_cfg_add_i32(fw_cfg, FW_CFG_PPC_BUSFREQ, BUSFREQ);
 
     qemu_register_boot_set(fw_cfg_boot_set, fw_cfg);
 }
diff --git a/include/hw/ppc/ppc.h b/include/hw/ppc/ppc.h
index d71bd07497..7e16e2e06c 100644
--- a/include/hw/ppc/ppc.h
+++ b/include/hw/ppc/ppc.h
@@ -92,6 +92,8 @@ enum {
 #define FW_CFG_PPC_IS_KVM       (FW_CFG_ARCH_LOCAL + 0x05)
 #define FW_CFG_PPC_KVM_HC       (FW_CFG_ARCH_LOCAL + 0x06)
 #define FW_CFG_PPC_KVM_PID      (FW_CFG_ARCH_LOCAL + 0x07)
+/* OpenBIOS has FW_CFG_PPC_NVRAM_ADDR as +0x08 */
+#define FW_CFG_PPC_BUSFREQ      (FW_CFG_ARCH_LOCAL + 0x09)
 
 #define PPC_SERIAL_MM_BAUDBASE 399193