diff --git a/lib/isc/task.c b/lib/isc/task.c
index 23f91c125b..0ea4487b0f 100644
--- a/lib/isc/task.c
+++ b/lib/isc/task.c
@@ -28,6 +28,8 @@
 	INSIST(isc_mutex_unlock((lp)) == ISC_R_SUCCESS);
 #define BROADCAST(cvp) \
 	INSIST(isc_condition_broadcast((cvp)) == ISC_R_SUCCESS);
+#define SIGNAL(cvp) \
+	INSIST(isc_condition_signal((cvp)) == ISC_R_SUCCESS);
 #define WAIT(cvp, lp) \
 	INSIST(isc_condition_wait((cvp), (lp)) == ISC_R_SUCCESS);
 #define WAITUNTIL(cvp, lp, tp, bp) \
@@ -303,7 +305,6 @@ isc_task_send(isc_task_t task, isc_event_t *eventp) {
 	}
 
 	if (was_idle) {
-		isc_boolean_t need_wakeup = ISC_FALSE;
 		isc_taskmgr_t manager;
 
 		/*
@@ -328,18 +329,9 @@ isc_task_send(isc_task_t task, isc_event_t *eventp) {
 		manager = task->manager;
 		INSIST(VALID_MANAGER(manager));
 		LOCK(&manager->lock);
-		if (EMPTY(manager->ready_tasks))
-			need_wakeup = ISC_TRUE;
 		ENQUEUE(manager->ready_tasks, task, ready_link);
+		SIGNAL(&manager->work_available);
 		UNLOCK(&manager->lock);
-
-		/*
-		 * If the runnable queue is empty, the worker threads could
-		 * either be executing tasks or waiting for something to do.
-		 * We wakeup anyone who is sleeping.
-		 */
-		if (need_wakeup)
-			BROADCAST(&manager->work_available);
 	}
 
 	*eventp = NULL;
@@ -416,19 +408,14 @@ isc_task_shutdown(isc_task_t task) {
 		return;
 
 	if (was_idle) {
-		isc_boolean_t need_wakeup = ISC_FALSE;
 		isc_taskmgr_t manager;
 
 		manager = task->manager;
 		INSIST(VALID_MANAGER(manager));
 		LOCK(&manager->lock);
-		if (EMPTY(manager->ready_tasks))
-			need_wakeup = ISC_TRUE;
 		ENQUEUE(manager->ready_tasks, task, ready_link);
+		SIGNAL(&manager->work_available);
 		UNLOCK(&manager->lock);
-
-		if (need_wakeup)
-			BROADCAST(&manager->work_available);
 	}
 }
 
diff --git a/lib/isc/timer.c b/lib/isc/timer.c
index f68ab46881..575c8da453 100644
--- a/lib/isc/timer.c
+++ b/lib/isc/timer.c
@@ -26,6 +26,8 @@
 	INSIST(isc_mutex_unlock((lp)) == ISC_R_SUCCESS);
 #define BROADCAST(cvp) \
 	INSIST(isc_condition_broadcast((cvp)) == ISC_R_SUCCESS);
+#define SIGNAL(cvp) \
+	INSIST(isc_condition_signal((cvp)) == ISC_R_SUCCESS);
 #define WAIT(cvp, lp) \
 	INSIST(isc_condition_wait((cvp), (lp)) == ISC_R_SUCCESS);
 #define WAITUNTIL(cvp, lp, tp) \
@@ -91,7 +93,7 @@ struct isc_timermgr {
 };
 
 static inline isc_result
-schedule(isc_timer_t timer, isc_time_t now, isc_boolean_t broadcast_ok) {
+schedule(isc_timer_t timer, isc_time_t now, isc_boolean_t signal_ok) {
 	isc_result result;
 	isc_timermgr_t manager;
 	struct isc_time due;
@@ -156,9 +158,9 @@ schedule(isc_timer_t timer, isc_time_t now, isc_boolean_t broadcast_ok) {
 	 * due time than the one the run thread is sleeping on, and we don't
 	 * want it to oversleep.
 	 */
-	if (timer->index == 1 && broadcast_ok) {
-		XTRACE("broadcast (schedule)");
-		BROADCAST(&manager->wakeup);
+	if (timer->index == 1 && signal_ok) {
+		XTRACE("signal (schedule)");
+		SIGNAL(&manager->wakeup);
 	}
 
 	return (ISC_R_SUCCESS);
@@ -182,8 +184,8 @@ deschedule(isc_timer_t timer) {
 		INSIST(manager->nscheduled > 0);
 		manager->nscheduled--;
 		if (need_wakeup) {
-			XTRACE("broadcast (deschedule)");
-			BROADCAST(&manager->wakeup);
+			XTRACE("signal (deschedule)");
+			SIGNAL(&manager->wakeup);
 		}
 	}
 }
@@ -620,8 +622,8 @@ isc_timermgr_destroy(isc_timermgr_t *managerp) {
 
 	UNLOCK(&manager->lock);
 
-	XTRACE("broadcast (destroy)");
-	BROADCAST(&manager->wakeup);
+	XTRACE("signal (destroy)");
+	SIGNAL(&manager->wakeup);
 
 	/*
 	 * Wait for thread to exit.