diff --git a/Documentation/NuttxPortingGuide.html b/Documentation/NuttxPortingGuide.html
index 7fa60d4d93b..8ecbf7abc7f 100644
--- a/Documentation/NuttxPortingGuide.html
+++ b/Documentation/NuttxPortingGuide.html
@@ -3915,7 +3915,7 @@ void sched_process_timer(void);
   The timer interrupt logic itself is implemented in the
   architecture specific code, but must call the following OS
   function periodically -- the calling interval must be
-  <code>MSEC_PER_TICK</code>.
+  <code>CONFIG_USEC_PER_TICK</code>.
 </p>
 
 <h3><a name="schedtimerexpiration">4.8.4 <code>sched_timer_expiration()</code></a></h3>
diff --git a/drivers/net/slip.c b/drivers/net/slip.c
index 4105314c78c..8b6af8d62d9 100644
--- a/drivers/net/slip.c
+++ b/drivers/net/slip.c
@@ -434,8 +434,8 @@ static void slip_txtask(int argc, FAR char *argv[])
   FAR struct slip_driver_s *priv;
   unsigned int index = *(argv[1]) - '0';
   net_lock_t flags;
-  systime_t msec_start;
-  systime_t msec_now;
+  systime_t start_ticks;
+  systime_t now_ticks;
   unsigned int hsec;
 
   nerr("index: %d\n", index);
@@ -450,7 +450,7 @@ static void slip_txtask(int argc, FAR char *argv[])
 
   /* Loop forever */
 
-  msec_start = clock_systimer() * MSEC_PER_TICK;
+  start_ticks = clock_systimer();
   for (;  ; )
     {
       /* Wait for the timeout to expire (or until we are signaled by by  */
@@ -484,14 +484,14 @@ static void slip_txtask(int argc, FAR char *argv[])
 
           /* Has a half second elapsed since the last timer poll? */
 
-          msec_now = clock_systimer() * MSEC_PER_TICK;
-          hsec = (unsigned int)(msec_now - msec_start) / (MSEC_PER_SEC / 2);
+          now_ticks = clock_systimer();
+          hsec = (unsigned int)(now_ticks - start_ticks) / TICK_PER_HSEC;
           if (hsec)
             {
               /* Yes, perform the timer poll */
 
               (void)devif_timer(&priv->dev, slip_txpoll);
-              msec_start += hsec * (MSEC_PER_SEC / 2);
+              start_ticks += hsec * TICK_PER_HSEC;
             }
           else
             {
diff --git a/fs/nfs/nfs.h b/fs/nfs/nfs.h
index f0db29389cf..2001e2b6b51 100644
--- a/fs/nfs/nfs.h
+++ b/fs/nfs/nfs.h
@@ -54,7 +54,6 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-#define NFS_TICKINTVL      MSEC_PER_TICK  /* Smallest that we can get */
 #define NFS_TICKS          1              /* Number of system ticks */
 #define NFS_HZ             CLOCKS_PER_SEC /* Ticks/sec */
 #define NFS_TIMEO          (1 * NFS_HZ)   /* Default timeout = 1 second */
diff --git a/include/nuttx/arch.h b/include/nuttx/arch.h
index 93a595a44ae..c1eacf0bd9f 100644
--- a/include/nuttx/arch.h
+++ b/include/nuttx/arch.h
@@ -1934,7 +1934,7 @@ void up_cxxinitialize(void);
  *   CONFIG_SCHED_TICKLESS is *not* defined).  The timer interrupt logic
  *   itself is implemented in the architecture specific code, but must call
  *   the following OS function periodically -- the calling interval must
- *   be MSEC_PER_TICK.
+ *   be CONFIG_USEC_PER_TICK.
  *
  ****************************************************************************/