Index: kernel/generic/include/atomic.h
===================================================================
--- kernel/generic/include/atomic.h	(revision 78de83de52a9115dc77b09bb7029403dad8c2fb0)
+++ kernel/generic/include/atomic.h	(revision 077842c7d8763d465a4900cd0693e65cd9338385)
@@ -42,6 +42,4 @@
 typedef size_t atomic_count_t;
 typedef ssize_t atomic_signed_t;
-
-#define PRIua  "zu"          /**< Format for atomic_count_t. */
 
 typedef struct {
Index: kernel/generic/src/proc/scheduler.c
===================================================================
--- kernel/generic/src/proc/scheduler.c	(revision 78de83de52a9115dc77b09bb7029403dad8c2fb0)
+++ kernel/generic/src/proc/scheduler.c	(revision 077842c7d8763d465a4900cd0693e65cd9338385)
@@ -530,5 +530,5 @@
 	log(LF_OTHER, LVL_DEBUG,
 	    "cpu%u: tid %" PRIu64 " (priority=%d, ticks=%" PRIu64
-	    ", nrdy=%" PRIua ")", CPU->id, THREAD->tid, THREAD->priority,
+	    ", nrdy=%zu)", CPU->id, THREAD->tid, THREAD->priority,
 	    THREAD->ticks, atomic_get(&CPU->nrdy));
 #endif
@@ -739,5 +739,5 @@
 		irq_spinlock_lock(&cpus[cpu].lock, true);
 
-		printf("cpu%u: address=%p, nrdy=%" PRIua ", needs_relink=%zu\n",
+		printf("cpu%u: address=%p, nrdy=%zu, needs_relink=%zu\n",
 		    cpus[cpu].id, &cpus[cpu], atomic_get(&cpus[cpu].nrdy),
 		    cpus[cpu].needs_relink);
Index: kernel/generic/src/proc/task.c
===================================================================
--- kernel/generic/src/proc/task.c	(revision 78de83de52a9115dc77b09bb7029403dad8c2fb0)
+++ kernel/generic/src/proc/task.c	(revision 077842c7d8763d465a4900cd0693e65cd9338385)
@@ -619,5 +619,5 @@
 #ifdef __32_BITS__
 	if (*additional)
-		printf("%-8" PRIu64 " %9" PRIua, task->taskid,
+		printf("%-8" PRIu64 " %9zu", task->taskid,
 		    atomic_get(&task->refcount));
 	else
@@ -631,5 +631,5 @@
 	if (*additional)
 		printf("%-8" PRIu64 " %9" PRIu64 "%c %9" PRIu64 "%c "
-		    "%9" PRIua "\n", task->taskid, ucycles, usuffix, kcycles,
+		    "%9zu\n", task->taskid, ucycles, usuffix, kcycles,
 		    ksuffix, atomic_get(&task->refcount));
 	else
Index: kernel/test/mm/falloc2.c
===================================================================
--- kernel/test/mm/falloc2.c	(revision 78de83de52a9115dc77b09bb7029403dad8c2fb0)
+++ kernel/test/mm/falloc2.c	(revision 077842c7d8763d465a4900cd0693e65cd9338385)
@@ -131,5 +131,5 @@
 
 	while (atomic_get(&thread_count) > 0) {
-		TPRINTF("Threads left: %" PRIua "\n",
+		TPRINTF("Threads left: %zu\n",
 		    atomic_get(&thread_count));
 		thread_sleep(1);
Index: kernel/test/synch/semaphore1.c
===================================================================
--- kernel/test/synch/semaphore1.c	(revision 78de83de52a9115dc77b09bb7029403dad8c2fb0)
+++ kernel/test/synch/semaphore1.c	(revision 077842c7d8763d465a4900cd0693e65cd9338385)
@@ -88,5 +88,5 @@
 		producers = (4 - i) * PRODUCERS;
 
-		TPRINTF("Creating %" PRIua " consumers and %" PRIua " producers...",
+		TPRINTF("Creating %zu consumers and %zu producers...",
 		    consumers, producers);
 
@@ -116,5 +116,5 @@
 
 		while ((items_consumed.count != consumers) || (items_produced.count != producers)) {
-			TPRINTF("%" PRIua " consumers remaining, %" PRIua " producers remaining\n",
+			TPRINTF("%zu consumers remaining, %zu producers remaining\n",
 			    consumers - items_consumed.count, producers - items_produced.count);
 			thread_sleep(1);
Index: kernel/test/synch/workq-test-core.h
===================================================================
--- kernel/test/synch/workq-test-core.h	(revision 78de83de52a9115dc77b09bb7029403dad8c2fb0)
+++ kernel/test/synch/workq-test-core.h	(revision 077842c7d8763d465a4900cd0693e65cd9338385)
@@ -191,9 +191,9 @@
 	for (int i = 0; i < WAVES; ++i) {
 		if (atomic_get(&call_cnt[i]) == exp_call_cnt) {
-			TPRINTF("Ok: %" PRIua " calls in wave %d, as expected.\n",
+			TPRINTF("Ok: %zu calls in wave %d, as expected.\n",
 			    atomic_get(&call_cnt[i]), i);
 		} else {
 			success = false;
-			TPRINTF("Error: %" PRIua " calls in wave %d, but %zu expected.\n",
+			TPRINTF("Error: %zu calls in wave %d, but %zu expected.\n",
 			    atomic_get(&call_cnt[i]), i, exp_call_cnt);
 		}
Index: kernel/test/thread/thread1.c
===================================================================
--- kernel/test/thread/thread1.c	(revision 78de83de52a9115dc77b09bb7029403dad8c2fb0)
+++ kernel/test/thread/thread1.c	(revision 077842c7d8763d465a4900cd0693e65cd9338385)
@@ -77,5 +77,5 @@
 	atomic_set(&finish, 0);
 	while (atomic_get(&threads_finished) < total) {
-		TPRINTF("Threads left: %" PRIua "\n", total - atomic_get(&threads_finished));
+		TPRINTF("Threads left: %zu\n", total - atomic_get(&threads_finished));
 		thread_sleep(1);
 	}