diff --git a/lib/isc/include/isc/timer.h b/lib/isc/include/isc/timer.h
index 03b52fc6b3..83d04a97cb 100644
--- a/lib/isc/include/isc/timer.h
+++ b/lib/isc/include/isc/timer.h
@@ -130,11 +130,15 @@ isc_timer_create(isc_timermgr_t *manager,
  *	'interval' seconds.  The value of 'expires' is ignored.
  *
  *	For once timers, 'expires' specifies the time when a life timeout
- *	event should be generated.  If 'expires' is 0, then no life
+ *	event should be generated.  If 'expires' is 0 (the epoch), then no life
  *	timeout will be generated.  'interval' specifies how long the timer
  *	can be idle before it generates an idle timeout.  If 0, then no
  *	idle timeout will be generated.
  *
+ *	If 'expires' is NULL, the epoch will be used.
+ *
+ *	If 'interval' is NULL, the zero interval will be used.
+ *
  * Requires:
  *
  *	'manager' is a valid manager
@@ -143,8 +147,12 @@ isc_timer_create(isc_timermgr_t *manager,
  *
  *	'action' is a valid action
  *
- *	(type == isc_timertype_inactive && expires == NULL && interval == NULL)
- *	|| ('expires' and 'interval' are not both 0)
+ *	'expires' points to a valid time, or is NULL.
+ *
+ *	'interval' points to a valid interval, or is NULL.
+ *
+ *	type == isc_timertype_inactive ||
+ *	('expires' and 'interval' are not both 0)
  *
  *	'timerp' is a valid pointer, and *timerp == NULL
  *
@@ -175,7 +183,13 @@ isc_timer_reset(isc_timer_t *timer,
  * Change the timer's type, expires, and interval values to the given
  * values.  If 'purge' is TRUE, any pending events from this timer
  * are purged from its task's event queue.
- *	
+ *
+ * Notes:
+ *
+ *	If 'expires' is NULL, the epoch will be used.
+ *
+ *	If 'interval' is NULL, the zero interval will be used.
+ *
  * Requires:
  *
  *	'timer' is a valid timer
diff --git a/lib/isc/timer.c b/lib/isc/timer.c
index 505e9280a0..8aabb4e9af 100644
--- a/lib/isc/timer.c
+++ b/lib/isc/timer.c
@@ -234,18 +234,21 @@ isc_timer_create(isc_timermgr_t *manager, isc_timertype_t type,
 	REQUIRE(VALID_MANAGER(manager));
 	REQUIRE(task != NULL);
 	REQUIRE(action != NULL);
-	REQUIRE((type == isc_timertype_inactive &&
-		 expires == NULL && interval == NULL) ||
+	if (expires == NULL)
+		expires = isc_time_epoch;
+	if (interval == NULL)
+		interval = isc_interval_zero;
+	REQUIRE(type == isc_timertype_inactive ||
 		!(isc_time_isepoch(expires) && isc_interval_iszero(interval)));
 	REQUIRE(timerp != NULL && *timerp == NULL);
 
 	/*
 	 * Get current time.
 	 */
-	result = isc_time_get(&now);
+	result = isc_time_now(&now);
 	if (result != ISC_R_SUCCESS) {
 		UNEXPECTED_ERROR(__FILE__, __LINE__,
-				 "isc_time_get() failed: %s",
+				 "isc_time_now() failed: %s",
 				 isc_result_totext(result));
 		return (ISC_R_UNEXPECTED);
 	}
@@ -326,17 +329,20 @@ isc_timer_reset(isc_timer_t *timer, isc_timertype_t type,
 	REQUIRE(VALID_TIMER(timer));
 	manager = timer->manager;
 	REQUIRE(VALID_MANAGER(manager));
-	REQUIRE((type == isc_timertype_inactive &&
-		 expires == NULL && interval == NULL) ||
+	if (expires == NULL)
+		expires = isc_time_epoch;
+	if (interval == NULL)
+		interval = isc_interval_zero;
+	REQUIRE(type == isc_timertype_inactive ||
 		!(isc_time_isepoch(expires) && isc_interval_iszero(interval)));
 
 	/*
 	 * Get current time.
 	 */
-	result = isc_time_get(&now);
+	result = isc_time_now(&now);
 	if (result != ISC_R_SUCCESS) {
 		UNEXPECTED_ERROR(__FILE__, __LINE__,
-				 "isc_time_get() failed: %s",
+				 "isc_time_now() failed: %s",
 				 isc_result_totext(result));
 		return (ISC_R_UNEXPECTED);
 	}
@@ -392,10 +398,10 @@ isc_timer_touch(isc_timer_t *timer) {
 	 * don't want to do.
 	 */
 
-	result = isc_time_get(&now);
+	result = isc_time_now(&now);
 	if (result != ISC_R_SUCCESS) {
 		UNEXPECTED_ERROR(__FILE__, __LINE__,
-				 "isc_time_get() failed: %s",
+				 "isc_time_now() failed: %s",
 				 isc_result_totext(result));
 		return (ISC_R_UNEXPECTED);
 	}
@@ -537,7 +543,7 @@ run(void *uap) {
 
 	LOCK(&manager->lock);
 	while (!manager->done) {
-		RUNTIME_CHECK(isc_time_get(&now) == ISC_R_SUCCESS);
+		RUNTIME_CHECK(isc_time_now(&now) == ISC_R_SUCCESS);
 
 		XTRACETIME("running", now);