diff --git a/arch/8051/src/up_unblocktask.c b/arch/8051/src/up_unblocktask.c
index d285ddbd274..cb4e65fc0b5 100644
--- a/arch/8051/src/up_unblocktask.c
+++ b/arch/8051/src/up_unblocktask.c
@@ -100,7 +100,7 @@ void up_unblock_task(FAR struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/arm/src/arm/up_unblocktask.c b/arch/arm/src/arm/up_unblocktask.c
index 64536d959d7..3476441b410 100644
--- a/arch/arm/src/arm/up_unblocktask.c
+++ b/arch/arm/src/arm/up_unblocktask.c
@@ -97,7 +97,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/arm/src/armv6-m/up_unblocktask.c b/arch/arm/src/armv6-m/up_unblocktask.c
index 0d51d21ca51..7a76a24d834 100644
--- a/arch/arm/src/armv6-m/up_unblocktask.c
+++ b/arch/arm/src/armv6-m/up_unblocktask.c
@@ -96,7 +96,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/arm/src/armv7-a/arm_unblocktask.c b/arch/arm/src/armv7-a/arm_unblocktask.c
index f08ceeca37b..c5ca090928b 100644
--- a/arch/arm/src/armv7-a/arm_unblocktask.c
+++ b/arch/arm/src/armv7-a/arm_unblocktask.c
@@ -97,7 +97,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/arm/src/armv7-m/up_unblocktask.c b/arch/arm/src/armv7-m/up_unblocktask.c
index 551e5b67bd3..f2455e594a9 100644
--- a/arch/arm/src/armv7-m/up_unblocktask.c
+++ b/arch/arm/src/armv7-m/up_unblocktask.c
@@ -97,7 +97,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/arm/src/c5471/c5471_timerisr.c b/arch/arm/src/c5471/c5471_timerisr.c
index 1021fb84ad9..fc1143162d8 100644
--- a/arch/arm/src/c5471/c5471_timerisr.c
+++ b/arch/arm/src/c5471/c5471_timerisr.c
@@ -53,7 +53,7 @@
  ************************************************************/
 
 /* We want the general purpose timer running at the rate
- * MSEC_PER_TICK. The C5471 clock is 47.5MHz and we're using
+ * USEC_PER_TICK. The C5471 clock is 47.5MHz and we're using
  * a timer PTV value of 3 (3 == divide incoming frequency by
  * 16) which then yields a 16 bitCLKS_PER_INT value
  * of 29687.
@@ -114,7 +114,7 @@ void up_timer_initialize(void)
   up_disable_irq(C5471_IRQ_SYSTIMER);
 
   /* Start the general purpose timer running in auto-reload mode
-   * so that an interrupt is generated at the rate MSEC_PER_TICK.
+   * so that an interrupt is generated at the rate USEC_PER_TICK.
    */
 
   val = ((CLKS_PER_INT-1) << CLKS_PER_INT_SHIFT) | AR | ST | PTV;
diff --git a/arch/arm/src/dm320/dm320_timerisr.c b/arch/arm/src/dm320/dm320_timerisr.c
index a92478aa335..fae34071486 100644
--- a/arch/arm/src/dm320/dm320_timerisr.c
+++ b/arch/arm/src/dm320/dm320_timerisr.c
@@ -139,7 +139,7 @@ void up_timer_initialize(void)
   up_disable_irq(DM320_IRQ_SYSTIMER);
 
   /* Start timer0 running so that an interrupt is generated at
-   * the rate MSEC_PER_TICK.
+   * the rate USEC_PER_TICK.
    */
 
   putreg16(DM320_TMR0_PRSCL, DM320_TIMER0_TMPRSCL); /* Timer 0 Prescalar */
diff --git a/arch/arm/src/imx/imx_timerisr.c b/arch/arm/src/imx/imx_timerisr.c
index 64db2e06d7f..d21b804c60c 100644
--- a/arch/arm/src/imx/imx_timerisr.c
+++ b/arch/arm/src/imx/imx_timerisr.c
@@ -138,11 +138,11 @@ void up_timer_initialize(void)
    * putreg(0, IMX_TIMER1_TPRER); -- already the case
    *
    * Set the compare register so that the COMP interrupt is generated
-   * with a period of MSEC_PER_TICK.  The value IMX_PERCLK1_FREQ/1000
+   * with a period of USEC_PER_TICK.  The value IMX_PERCLK1_FREQ/1000
    * (defined in board.h) is the number of counts in millisecond, so:
    */
 
-   putreg32((IMX_PERCLK1_FREQ / 1000) * MSEC_PER_TICK, IMX_TIMER1_TCMP);
+   putreg32(MSEC2TICK(IMX_PERCLK1_FREQ / 1000), IMX_TIMER1_TCMP);
 
   /* Configure to provide timer COMP interrupts when TCN increments
    * to TCMP.
diff --git a/arch/arm/src/kinetis/kinetis_sdhc.c b/arch/arm/src/kinetis/kinetis_sdhc.c
index 3ba8c42996e..6ff5092e5cc 100644
--- a/arch/arm/src/kinetis/kinetis_sdhc.c
+++ b/arch/arm/src/kinetis/kinetis_sdhc.c
@@ -2409,7 +2409,7 @@ static sdio_eventset_t kinetis_eventwait(FAR struct sdio_dev_s *dev,
 
       /* Start the watchdog timer */
 
-      delay = (timeout + (MSEC_PER_TICK-1)) / MSEC_PER_TICK;
+      delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)kinetis_eventtimeout,
                        1, (uint32_t)priv);
       if (ret != OK)
diff --git a/arch/arm/src/lpc17xx/lpc17_sdcard.c b/arch/arm/src/lpc17xx/lpc17_sdcard.c
index 0fd719f24f4..d5b143118d2 100644
--- a/arch/arm/src/lpc17xx/lpc17_sdcard.c
+++ b/arch/arm/src/lpc17xx/lpc17_sdcard.c
@@ -2266,7 +2266,7 @@ static sdio_eventset_t lpc17_eventwait(FAR struct sdio_dev_s *dev,
 
       /* Start the watchdog timer */
 
-      delay = (timeout + (MSEC_PER_TICK-1)) / MSEC_PER_TICK;
+      delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)lpc17_eventtimeout,
                        1, (uint32_t)priv);
       if (ret != OK)
diff --git a/arch/arm/src/sam34/sam_hsmci.c b/arch/arm/src/sam34/sam_hsmci.c
index 94d052bd169..d770b2d2be0 100644
--- a/arch/arm/src/sam34/sam_hsmci.c
+++ b/arch/arm/src/sam34/sam_hsmci.c
@@ -2273,7 +2273,7 @@ static sdio_eventset_t sam_eventwait(FAR struct sdio_dev_s *dev,
 
       /* Start the watchdog timer */
 
-      delay = (timeout + (MSEC_PER_TICK-1)) / MSEC_PER_TICK;
+      delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)sam_eventtimeout,
                        1, (uint32_t)priv);
       if (ret != OK)
diff --git a/arch/arm/src/sam34/sam_spi.c b/arch/arm/src/sam34/sam_spi.c
index 5e32faf698e..81c73a76f68 100644
--- a/arch/arm/src/sam34/sam_spi.c
+++ b/arch/arm/src/sam34/sam_spi.c
@@ -127,7 +127,7 @@
  */
 
 #define DMA_TIMEOUT_MS    (800)
-#define DMA_TIMEOUT_TICKS ((DMA_TIMEOUT_MS + (MSEC_PER_TICK-1)) / MSEC_PER_TICK)
+#define DMA_TIMEOUT_TICKS MSEC2TICK(DMA_TIMEOUT_MS)
 
 /* Debug *******************************************************************/
 /* Check if SPI debut is enabled (non-standard.. no support in
diff --git a/arch/arm/src/sama5/sam_hsmci.c b/arch/arm/src/sama5/sam_hsmci.c
index f0a0d3be1e5..670c3a69f7e 100644
--- a/arch/arm/src/sama5/sam_hsmci.c
+++ b/arch/arm/src/sama5/sam_hsmci.c
@@ -2737,7 +2737,7 @@ static sdio_eventset_t sam_eventwait(FAR struct sdio_dev_s *dev,
           timeout = MAX(5000, timeout);
         }
 
-      delay = (timeout + (MSEC_PER_TICK-1)) / MSEC_PER_TICK;
+      delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)sam_eventtimeout,
                        1, (uint32_t)priv);
       if (ret != OK)
diff --git a/arch/arm/src/sama5/sam_spi.c b/arch/arm/src/sama5/sam_spi.c
index 10469107720..3a1a4652a7d 100644
--- a/arch/arm/src/sama5/sam_spi.c
+++ b/arch/arm/src/sama5/sam_spi.c
@@ -120,7 +120,7 @@
  */
 
 #define DMA_TIMEOUT_MS    (800)
-#define DMA_TIMEOUT_TICKS ((DMA_TIMEOUT_MS + (MSEC_PER_TICK-1)) / MSEC_PER_TICK)
+#define DMA_TIMEOUT_TICKS MSEC2TICK(DMA_TIMEOUT_MS)
 
 /* Debug *******************************************************************/
 /* Check if SPI debut is enabled (non-standard.. no support in
diff --git a/arch/arm/src/sama5/sam_ssc.c b/arch/arm/src/sama5/sam_ssc.c
index 475cf06b2e2..570b85078a6 100644
--- a/arch/arm/src/sama5/sam_ssc.c
+++ b/arch/arm/src/sama5/sam_ssc.c
@@ -390,7 +390,7 @@
  */
 
 #define DMA_TIMEOUT_MS    (800)
-#define DMA_TIMEOUT_TICKS ((DMA_TIMEOUT_MS + (MSEC_PER_TICK-1)) / MSEC_PER_TICK)
+#define DMA_TIMEOUT_TICKS MSEC2TICK(DMA_TIMEOUT_MS)
 
 /* Debug *******************************************************************/
 /* Check if SSC debut is enabled (non-standard.. no support in
diff --git a/arch/arm/src/sama5/sam_tsd.c b/arch/arm/src/sama5/sam_tsd.c
index c3d45307f00..fe73afc3dc4 100644
--- a/arch/arm/src/sama5/sam_tsd.c
+++ b/arch/arm/src/sama5/sam_tsd.c
@@ -89,7 +89,7 @@
 
 /* Poll the pen position while the pen is down at this rate (50MS): */
 
-#define TSD_WDOG_DELAY      ((50 + (MSEC_PER_TICK-1))/ MSEC_PER_TICK)
+#define TSD_WDOG_DELAY      MSEC2TICK(50)
 
 /* This is a value for the threshold that guantees a big difference on the
  * first pendown (but can't overflow).
diff --git a/arch/arm/src/sama5/sam_twi.c b/arch/arm/src/sama5/sam_twi.c
index 2e1c6a1a92b..eec19f6e60e 100644
--- a/arch/arm/src/sama5/sam_twi.c
+++ b/arch/arm/src/sama5/sam_twi.c
@@ -527,7 +527,7 @@ static int twi_wait(struct twi_dev_s *priv, unsigned int size)
    * There is no concern about arithmetic overflow for reasonable transfer sizes.
    */
 
-  timeout = (TWI_TIMEOUT_MSPB * size) / MSEC_PER_TICK;
+  timeout = MSEC2TICK(TWI_TIMEOUT_MSPB);
   if (timeout < 1)
     {
       timeout = 1;
diff --git a/arch/arm/src/stm32/stm32_otgfshost.c b/arch/arm/src/stm32/stm32_otgfshost.c
index 7866365d927..7fe99c1c37b 100644
--- a/arch/arm/src/stm32/stm32_otgfshost.c
+++ b/arch/arm/src/stm32/stm32_otgfshost.c
@@ -151,8 +151,8 @@
 
 #define STM32_READY_DELAY         200000 /* In loop counts */
 #define STM32_FLUSH_DELAY         200000 /* In loop counts */
-#define STM32_SETUP_DELAY         (5000 / MSEC_PER_TICK) /* 5 seconds in system ticks */
-#define STM32_DATANAK_DELAY       (5000 / MSEC_PER_TICK) /* 5 seconds in system ticks */
+#define STM32_SETUP_DELAY         SEC2TICK(5) /* 5 seconds in system ticks */
+#define STM32_DATANAK_DELAY       SEC2TICK(5) /* 5 seconds in system ticks */
 
 /* Ever-present MIN/MAX macros */
 
diff --git a/arch/arm/src/stm32/stm32_sdio.c b/arch/arm/src/stm32/stm32_sdio.c
index f731ad75cc8..cc164bc8018 100644
--- a/arch/arm/src/stm32/stm32_sdio.c
+++ b/arch/arm/src/stm32/stm32_sdio.c
@@ -2315,7 +2315,7 @@ static sdio_eventset_t stm32_eventwait(FAR struct sdio_dev_s *dev,
 
       /* Start the watchdog timer */
 
-      delay = (timeout + (MSEC_PER_TICK-1)) / MSEC_PER_TICK;
+      delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)stm32_eventtimeout,
                        1, (uint32_t)priv);
       if (ret != OK)
diff --git a/arch/avr/src/avr/up_unblocktask.c b/arch/avr/src/avr/up_unblocktask.c
index 305e057a8c5..6fb2e67e5ca 100644
--- a/arch/avr/src/avr/up_unblocktask.c
+++ b/arch/avr/src/avr/up_unblocktask.c
@@ -97,7 +97,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/avr/src/avr32/up_unblocktask.c b/arch/avr/src/avr32/up_unblocktask.c
index 42dc3d52aab..f53550da90d 100644
--- a/arch/avr/src/avr32/up_unblocktask.c
+++ b/arch/avr/src/avr32/up_unblocktask.c
@@ -97,7 +97,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/hc/src/common/up_unblocktask.c b/arch/hc/src/common/up_unblocktask.c
index 08cefc1d4bc..425db0f9812 100644
--- a/arch/hc/src/common/up_unblocktask.c
+++ b/arch/hc/src/common/up_unblocktask.c
@@ -97,7 +97,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/mips/src/mips32/up_unblocktask.c b/arch/mips/src/mips32/up_unblocktask.c
index 277ec79cf37..dab958b159f 100644
--- a/arch/mips/src/mips32/up_unblocktask.c
+++ b/arch/mips/src/mips32/up_unblocktask.c
@@ -99,7 +99,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/rgmp/src/nuttx.c b/arch/rgmp/src/nuttx.c
index e6fee5de1da..0178ae58af0 100644
--- a/arch/rgmp/src/nuttx.c
+++ b/arch/rgmp/src/nuttx.c
@@ -326,7 +326,7 @@ void up_unblock_task(struct tcb_s *tcb)
          * robin tasks but it doesn't here to do it for everything
          */
 #if CONFIG_RR_INTERVAL > 0
-        tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+        tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
         // Add the task in the correct location in the prioritized
diff --git a/arch/sh/src/common/up_unblocktask.c b/arch/sh/src/common/up_unblocktask.c
index 5ba0173fbd2..a4b598499d5 100644
--- a/arch/sh/src/common/up_unblocktask.c
+++ b/arch/sh/src/common/up_unblocktask.c
@@ -97,7 +97,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/sim/src/up_tickless.c b/arch/sim/src/up_tickless.c
index 57a7935347f..4e04cd71e23 100644
--- a/arch/sim/src/up_tickless.c
+++ b/arch/sim/src/up_tickless.c
@@ -66,6 +66,7 @@
 #include <time.h>
 
 #include <nuttx/arch.h>
+#include <nuttx/clock.h>
 
 #ifdef CONFIG_SCHED_TICKLESS
 
@@ -74,12 +75,12 @@
  ****************************************************************************/
 
 #if defined(CONFIG_SIM_WALLTIME) || defined(CONFIG_SIM_X11FB)
-#  define TICK_USEC (1000000 / CLK_TCK)
-#  define TICK_SEC  (TICK_USEC / 1000000)
-#  define TICK_NSEC ((TICK_USEC % 1000) * 1000)
+#  define TICK_USEC (USEC_PER_SEC / CLK_TCK)
+#  define TICK_SEC  (TICK_USEC / USEC_PER_SEC)
+#  define TICK_NSEC ((TICK_USEC % NSEC_PER_USEC) * NSEC_PER_USEC)
 #else
-#  define TICK_SEC 0
-#  define TICK_NSEC (128 * 1000)
+#  define TICK_SEC  0
+#  define TICK_NSEC NSEC_PER_TICK
 #endif
 
 /****************************************************************************
@@ -209,8 +210,8 @@ int up_timer_cancel(FAR struct timespec *ts)
 
   if (g_timer_active)
     {
-      ts->tv_sec  = g_interval_delay.tv_nsec;
-      ts->tv_nsec = g_interval_delay.tv_sec;
+      ts->tv_sec  = g_interval_delay.tv_sec;
+      ts->tv_nsec = g_interval_delay.tv_nsec;
     }
   else
     {
@@ -220,8 +221,8 @@ int up_timer_cancel(FAR struct timespec *ts)
 
   /* Disable and reset the simulated timer */
 
-  g_interval_delay.tv_nsec = 0;
   g_interval_delay.tv_sec  = 0;
+  g_interval_delay.tv_nsec = 0;
   g_timer_active           = false;
 }
 #endif
@@ -253,8 +254,8 @@ int up_timer_cancel(FAR struct timespec *ts)
 #ifdef CONFIG_SCHED_TICKLESS
 int up_timer_start(FAR const struct timespec *ts)
 {
-  g_interval_delay.tv_nsec = ts->tv_nsec;
   g_interval_delay.tv_sec  = ts->tv_sec;
+  g_interval_delay.tv_nsec = ts->tv_nsec;
   g_timer_active           = true;
 }
 #endif
@@ -278,10 +279,10 @@ void up_timer_update(void)
   /* Increment the elapsed time */
 
   g_elapsed_time.tv_nsec += TICK_NSEC;
-  if (g_elapsed_time.tv_nsec >= 1000000000)
+  if (g_elapsed_time.tv_nsec >= NSEC_PER_SEC)
     {
-      g_elapsed_time.tv_nsec++;
-      g_elapsed_time.tv_sec -= 1000000000;
+      g_elapsed_time.tv_sec++;
+      g_elapsed_time.tv_nsec -= NSEC_PER_SEC;
     }
 
   g_elapsed_time.tv_sec += TICK_SEC;
@@ -307,7 +308,7 @@ void up_timer_update(void)
 
           /* Decrement nanoseconds */
 
-          if (g_interval_delay.tv_nsec > TICK_NSEC)
+          if (g_interval_delay.tv_nsec >= TICK_NSEC)
             {
               g_interval_delay.tv_nsec -= TICK_NSEC;
             }
@@ -316,14 +317,10 @@ void up_timer_update(void)
 
           else if (g_interval_delay.tv_sec > 0)
             {
-              if (g_interval_delay.tv_nsec >= TICK_NSEC)
-                {
-                  g_interval_delay.tv_nsec = 0;
-                }
-              else
-                {
-                  g_interval_delay.tv_sec--;
-                }
+              g_interval_delay.tv_nsec += NSEC_PER_SEC;
+              g_interval_delay.tv_sec--;
+
+              g_interval_delay.tv_nsec -= TICK_NSEC;
             }
 
           /* Otherwise the timer has expired */
diff --git a/arch/sim/src/up_unblocktask.c b/arch/sim/src/up_unblocktask.c
index 04c2349e476..2da05edcc41 100644
--- a/arch/sim/src/up_unblocktask.c
+++ b/arch/sim/src/up_unblocktask.c
@@ -99,7 +99,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/x86/src/common/up_unblocktask.c b/arch/x86/src/common/up_unblocktask.c
index 43b93c4e6db..9e5597f16c9 100644
--- a/arch/x86/src/common/up_unblocktask.c
+++ b/arch/x86/src/common/up_unblocktask.c
@@ -96,7 +96,7 @@ void up_unblock_task(struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/z16/src/common/up_unblocktask.c b/arch/z16/src/common/up_unblocktask.c
index 984e514ad8a..28bb9541784 100644
--- a/arch/z16/src/common/up_unblocktask.c
+++ b/arch/z16/src/common/up_unblocktask.c
@@ -101,7 +101,7 @@ void up_unblock_task(FAR struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized
diff --git a/arch/z80/src/common/up_unblocktask.c b/arch/z80/src/common/up_unblocktask.c
index 6c46b0a14d2..bc829db0d07 100644
--- a/arch/z80/src/common/up_unblocktask.c
+++ b/arch/z80/src/common/up_unblocktask.c
@@ -102,7 +102,7 @@ void up_unblock_task(FAR struct tcb_s *tcb)
    */
 
 #if CONFIG_RR_INTERVAL > 0
-  tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+  tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
 #endif
 
   /* Add the task in the correct location in the prioritized