diff --git a/src/avr/timer.c b/src/avr/timer.c
index 8cc3d550..538f0b19 100644
--- a/src/avr/timer.c
+++ b/src/avr/timer.c
@@ -8,18 +8,18 @@
 #include "command.h" // shutdown
 #include "irq.h" // irq_save
 #include "sched.h" // sched_timer_kick
-#include "timer.h" // timer_from_ms
+#include "timer.h" // timer_from_us
 
 
 /****************************************************************
  * Low level timer code
  ****************************************************************/
 
-// Return the number of clock ticks for a given number of milliseconds
+// Return the number of clock ticks for a given number of microseconds
 uint32_t
-timer_from_ms(uint32_t ms)
+timer_from_us(uint32_t us)
 {
-    return ms * (F_CPU / 1000);
+    return us * (F_CPU / 1000000);
 }
 
 static inline uint16_t
@@ -156,7 +156,7 @@ timer_try_set_next(uint32_t target)
     // Too many repeat timers from a single interrupt - force a pause
     timer_repeat = TIMER_MAX_NEXT_REPEAT;
     next = now + TIMER_DEFER_REPEAT_TICKS;
-    if (diff < (int16_t)(-timer_from_ms(1)))
+    if (diff < (int16_t)(-timer_from_us(1000)))
         goto fail;
 
 done:
diff --git a/src/avr/timer.h b/src/avr/timer.h
index 2165fecd..188d8a98 100644
--- a/src/avr/timer.h
+++ b/src/avr/timer.h
@@ -3,7 +3,7 @@
 
 #include <stdint.h>
 
-uint32_t timer_from_ms(uint32_t ms);
+uint32_t timer_from_us(uint32_t us);
 void timer_periodic(void);
 uint32_t timer_read_time(void);
 uint8_t timer_set_next(uint32_t next);
diff --git a/src/basecmd.c b/src/basecmd.c
index b94c820a..113cc30e 100644
--- a/src/basecmd.c
+++ b/src/basecmd.c
@@ -205,7 +205,7 @@ stats_task(void)
     sumsq = nextsumsq;
 
     static uint32_t prev;
-    if (sched_is_before(cur, prev + sched_from_ms(5000)))
+    if (sched_is_before(cur, prev + sched_from_us(5000000)))
         return;
     sendf("stats count=%u sum=%u sumsq=%u", count, cur - prev, sumsq);
     prev = cur;
diff --git a/src/sched.c b/src/sched.c
index 2f51515c..a25f43e2 100644
--- a/src/sched.c
+++ b/src/sched.c
@@ -9,9 +9,9 @@
 #include <stddef.h> // NULL
 #include "autoconf.h" // CONFIG_*
 #include "board/irq.h" // irq_save
-#include "board/timer.h" // timer_from_ms
+#include "board/timer.h" // timer_from_us
 #include "command.h" // shutdown
-#include "sched.h" // sched_from_ms
+#include "sched.h" // sched_from_us
 #include "stepper.h" // stepper_event
 
 
@@ -30,7 +30,7 @@ ms_event(struct timer *t)
 {
     millis++;
     timer_periodic();
-    t->waketime += sched_from_ms(1);
+    t->waketime += sched_from_us(1000);
     return SF_RESCHEDULE;
 }
 
@@ -52,11 +52,11 @@ sched_check_periodic(uint16_t time, uint16_t *pnext)
     return 1;
 }
 
-// Return the number of clock ticks for a given number of milliseconds
+// Return the number of clock ticks for a given number of microseconds
 uint32_t
-sched_from_ms(uint32_t ms)
+sched_from_us(uint32_t us)
 {
-    return timer_from_ms(ms);
+    return timer_from_us(us);
 }
 
 // Return the current time (in clock ticks)
diff --git a/src/sched.h b/src/sched.h
index 047ac1ce..be73ce65 100644
--- a/src/sched.h
+++ b/src/sched.h
@@ -23,7 +23,7 @@ enum { SF_DONE=0, SF_RESCHEDULE=1 };
 
 // sched.c
 uint8_t sched_check_periodic(uint16_t time, uint16_t *pnext);
-uint32_t sched_from_ms(uint32_t ms);
+uint32_t sched_from_us(uint32_t us);
 uint32_t sched_read_time(void);
 uint8_t sched_is_before(uint32_t time1, uint32_t time2);
 void sched_timer(struct timer*);
diff --git a/src/simulator/main.c b/src/simulator/main.c
index 2d43a138..e871864a 100644
--- a/src/simulator/main.c
+++ b/src/simulator/main.c
@@ -17,7 +17,7 @@ uint8_t Interrupt_off;
  ****************************************************************/
 
 uint32_t
-timer_from_ms(uint32_t ms)
+timer_from_us(uint32_t us)
 {
     return 0; // XXX
 }
diff --git a/src/simulator/timer.h b/src/simulator/timer.h
index f35b8278..71b64502 100644
--- a/src/simulator/timer.h
+++ b/src/simulator/timer.h
@@ -3,7 +3,7 @@
 
 #include <stdint.h>
 
-uint32_t timer_from_ms(uint32_t ms);
+uint32_t timer_from_us(uint32_t us);
 void timer_periodic(void);
 uint32_t timer_read_time(void);
 uint8_t timer_set_next(uint32_t next);