diff --git a/sys/dev/aic7xxx/aic79xx.reg b/sys/dev/aic7xxx/aic79xx.reg
index 0138ca27103..74c2e2bc66e 100644
--- a/sys/dev/aic7xxx/aic79xx.reg
+++ b/sys/dev/aic7xxx/aic79xx.reg
@@ -3931,7 +3931,8 @@ const PKT_OVERRUN_BUFSIZE	512
  */
 const AHD_TIMER_US_PER_TICK	25
 const AHD_TIMER_MAX_TICKS	0xFFFF
-const AHD_TIMER_MAX_US		(AHD_TIMER_MAX_TICKS * AHD_TIMER_US_PER_TICK)
+/*const AHD_TIMER_MAX_US	(AHD_TIMER_MAX_TICKS * AHD_TIMER_US_PER_TICK)*/
+const AHD_TIMER_MAX_US		1638375
 
 /*
  * Downloaded (kernel inserted) constants