diff --git a/kern/kern_systimer.c b/kern/kern_systimer.c
--- a/kern/kern_systimer.c
+++ b/kern/kern_systimer.c
@@ -265,6 +265,8 @@
 
     bzero(info, sizeof(struct systimer));
 
+    if (freq <= 0)
+	    freq = 1;
     if ((flags & SYSTF_100KHZSYNC) && freq <= 100000)
 	    info->periodic = sys_cputimer->fromhz(100000) * (100000 / freq);
     if ((flags & SYSTF_MSSYNC) && freq <= 1000)