diff --git a/c/src/lib/libcpu/arm/ChangeLog b/c/src/lib/libcpu/arm/ChangeLog
index 91d633c1dd..05771e3de1 100644
--- a/c/src/lib/libcpu/arm/ChangeLog
+++ b/c/src/lib/libcpu/arm/ChangeLog
@@ -1,3 +1,8 @@
+2009-08-04	Xi Yang <hiyangxi@gmail.com>
+
+	* pxa255/clock/clock.c: Move parentheses to improve math. More tests
+	run.
+
 2009-07-15	Sebastian Huber <sebastian.huber@embedded-brains.de>
 
 	* Makefile.am: Removed references to deleted file
diff --git a/c/src/lib/libcpu/arm/pxa255/clock/clock.c b/c/src/lib/libcpu/arm/pxa255/clock/clock.c
index 0bb96a00a3..ad26e57a64 100755
--- a/c/src/lib/libcpu/arm/pxa255/clock/clock.c
+++ b/c/src/lib/libcpu/arm/pxa255/clock/clock.c
@@ -40,7 +40,7 @@ static void clock_isr_on(const rtems_irq_connect_data *unused)
   /* enable timer interrupt */
   XSCALE_OS_TIMER_IER |= 0x1;
 
-  period_num = TIMER_RATE*(Configuration.microseconds_per_tick/10000);
+  period_num = (TIMER_RATE* Configuration.microseconds_per_tick)/10000;
 
   XSCALE_OS_TIMER_MR0 = XSCALE_OS_TIMER_TCR + period_num;
 }
@@ -90,7 +90,7 @@ rtems_irq_connect_data clock_isr_data = {
 
 void Clock_driver_support_initialize_hardware(void)
 {
-  period_num = TIMER_RATE*(Configuration.microseconds_per_tick/10000);
+  period_num = (TIMER_RATE* Configuration.microseconds_per_tick)/10000;
 }