diff --git a/Source/HBIOS/Config/ZETA_std.asm b/Source/HBIOS/Config/ZETA_std.asm
index da5515ce..d422cab9 100644
--- a/Source/HBIOS/Config/ZETA_std.asm
+++ b/Source/HBIOS/Config/ZETA_std.asm
@@ -26,7 +26,7 @@
 ;
 #include "cfg_zeta.asm"
 ;
-CPUOSC		.SET	20000000	; CPU OSC FREQ IN MHZ
+CPUOSC		.SET	8000000		; CPU OSC FREQ IN MHZ
 INTMODE		.SET	0		; INTERRUPTS: 0=NONE, 1=MODE 1, 2=MODE 2
 CRTACT		.SET	TRUE		; ACTIVATE CRT (VDU,CVDU,PROPIO,ETC) AT STARTUP
 ;