diff --git a/hw/ppc/mac_newworld.c b/hw/ppc/mac_newworld.c
index 3e796d2f6d..ff9e490c4e 100644
--- a/hw/ppc/mac_newworld.c
+++ b/hw/ppc/mac_newworld.c
@@ -77,7 +77,7 @@
 
 #define MAX_IDE_BUS 2
 #define CFG_ADDR 0xf0000510
-#define TBFREQ (100UL * 1000UL * 1000UL)
+#define TBFREQ (25UL * 1000UL * 1000UL)
 #define CLOCKFREQ (900UL * 1000UL * 1000UL)
 #define BUSFREQ (100UL * 1000UL * 1000UL)