diff --git a/sys/src/9/pc/i8253.c b/sys/src/9/pc/i8253.c
index 50fad7105..586f2387b 100644
--- a/sys/src/9/pc/i8253.c
+++ b/sys/src/9/pc/i8253.c
@@ -133,6 +133,7 @@ guesscpuhz(int aalcycles)
 	if(m->machno != 0){
 		m->cpuhz = MACHP(0)->cpuhz;
 		m->cpumhz = MACHP(0)->cpumhz;
+		m->cyclefreq = MACHP(0)->cyclefreq;
 		m->loopconst = MACHP(0)->loopconst;
 		return;
 	}