diff --git a/ChangeLog b/ChangeLog
index 1760ec4..554c49e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-11-18  NIIBE Yutaka  <gniibe@fsij.org>
+
+	* chopstx-cortex-m.c (ticks_to_usec): New.
+	* chopstx-gnu-linux.c (ticks_to_usec): New.
+	* chopstx.c (chx_snooze): Use ticks_to_usec.
+
 2019-11-18  NIIBE Yutaka  <gniibe@fsij.org>
 
 	* rules.mk (CSRC): Change the rule of entry*.c.
diff --git a/chopstx-cortex-m.c b/chopstx-cortex-m.c
index 23cfe03..ea824d9 100644
--- a/chopstx-cortex-m.c
+++ b/chopstx-cortex-m.c
@@ -141,6 +141,12 @@ static uint32_t usec_to_ticks (uint32_t usec)
   return usec * MHZ;
 }
 
+static uint32_t
+ticks_to_usec (uint32_t ticks)
+{
+  return ticks / MHZ;
+}
+
 /*
  * Interrupt Handling
  */
diff --git a/chopstx-gnu-linux.c b/chopstx-gnu-linux.c
index 9c7f8df..d9f9876 100644
--- a/chopstx-gnu-linux.c
+++ b/chopstx-gnu-linux.c
@@ -76,6 +76,11 @@ usec_to_ticks (uint32_t usec)
   return usec * MHZ;
 }
 
+static uint32_t
+ticks_to_usec (uint32_t ticks)
+{
+  return ticks / MHZ;
+}
 
 static void
 chx_enable_intr (uint8_t irq_num)
diff --git a/chopstx.c b/chopstx.c
index 022d821..74947d0 100644
--- a/chopstx.c
+++ b/chopstx.c
@@ -688,7 +688,7 @@ chx_snooze (uint32_t state, uint32_t *usec_p)
     *usec_p -= usec0;
   else if (r > 0)
     {
-      *usec_p -= (usec0 - r / MHZ);
+      *usec_p -= (usec0 - ticks_to_usec (r));
       r = 1;
     }