diff --git a/src/aio/aio.c b/src/aio/aio.c
index a1a3e791..a097de94 100644
--- a/src/aio/aio.c
+++ b/src/aio/aio.c
@@ -8,6 +8,7 @@
 #include <sys/auxv.h>
 #include "syscall.h"
 #include "atomic.h"
+#include "lock.h"
 #include "pthread_impl.h"
 #include "aio_impl.h"
 
@@ -71,6 +72,7 @@ struct aio_args {
 	sem_t sem;
 };
 
+static volatile int map_update_lock[1];
 static pthread_rwlock_t maplock = PTHREAD_RWLOCK_INITIALIZER;
 static struct aio_queue *****map;
 static volatile int aio_fd_cnt;
@@ -86,40 +88,62 @@ static struct aio_queue *__aio_get_queue(int fd, int need)
 		errno = EBADF;
 		return 0;
 	}
+	sigset_t allmask, origmask;
 	int a=fd>>24;
 	unsigned char b=fd>>16, c=fd>>8, d=fd;
-	struct aio_queue *q = 0;
+	struct aio_queue *****m = 0, ****ma = 0, ***mb = 0, **mc = 0, *q = 0;
+	int n = 0;
+
 	pthread_rwlock_rdlock(&maplock);
-	if ((!map || !map[a] || !map[a][b] || !map[a][b][c] || !(q=map[a][b][c][d])) && need) {
-		pthread_rwlock_unlock(&maplock);
-		if (fcntl(fd, F_GETFD) < 0) return 0;
-		pthread_rwlock_wrlock(&maplock);
+	if (map && map[a] && map[a][b] && map[a][b][c] && (q=map[a][b][c][d]))
+		pthread_mutex_lock(&q->lock);
+	pthread_rwlock_unlock(&maplock);
+
+	if (q || !need)
+		return q;
+	if (fcntl(fd, F_GETFD) < 0)
+		return 0;
+
+	LOCK(map_update_lock);
+	if (!map || !(n++, map[a]) || !(n++, map[a][b]) || !(n++, map[a][b][c]) || !(n++, q=map[a][b][c][d])) {
 		if (!io_thread_stack_size) {
 			unsigned long val = __getauxval(AT_MINSIGSTKSZ);
 			io_thread_stack_size = MAX(MINSIGSTKSZ+2048, val+512);
 		}
-		if (!map) map = calloc(sizeof *map, (-1U/2+1)>>24);
-		if (!map) goto out;
-		if (!map[a]) map[a] = calloc(sizeof **map, 256);
-		if (!map[a]) goto out;
-		if (!map[a][b]) map[a][b] = calloc(sizeof ***map, 256);
-		if (!map[a][b]) goto out;
-		if (!map[a][b][c]) map[a][b][c] = calloc(sizeof ****map, 256);
-		if (!map[a][b][c]) goto out;
-		if (!(q = map[a][b][c][d])) {
-			map[a][b][c][d] = q = calloc(sizeof *****map, 1);
-			if (q) {
-				q->fd = fd;
-				pthread_mutex_init(&q->lock, 0);
-				pthread_cond_init(&q->cond, 0);
-				a_inc(&aio_fd_cnt);
-			}
+		switch (n) {
+			case 0: if (!(m = calloc(sizeof *m, (-1U/2+1)>>24))) goto fail;
+			case 1: if (!(ma = calloc(sizeof *ma, 256))) goto fail;
+			case 2: if (!(mb = calloc(sizeof *mb, 256))) goto fail;
+			case 3: if (!(mc = calloc(sizeof *mc, 256))) goto fail;
+			case 4: if (!(q = calloc(sizeof *q, 1))) goto fail;
 		}
+		q->fd = fd;
+		pthread_mutex_init(&q->lock, 0);
+		pthread_cond_init(&q->cond, 0);
+		a_inc(&aio_fd_cnt);
 	}
-	if (q) pthread_mutex_lock(&q->lock);
-out:
+	sigfillset(&allmask);
+	pthread_sigmask(SIG_BLOCK, &allmask, &origmask);
+	pthread_rwlock_wrlock(&maplock);
+	switch (n) {
+		case 0: map = m;
+		case 1: map[a] = ma;
+		case 2: map[a][b] = mb;
+		case 3: map[a][b][c] = mc;
+		case 4: map[a][b][c][d] = q;
+	}
+	pthread_mutex_lock(&q->lock);
 	pthread_rwlock_unlock(&maplock);
+	pthread_sigmask(SIG_SETMASK, &origmask, 0);
+	UNLOCK(map_update_lock);
 	return q;
+fail:
+	UNLOCK(map_update_lock);
+	free(mc);
+	free(mb);
+	free(ma);
+	free(m);
+	return 0;
 }
 
 static void __aio_unref_queue(struct aio_queue *q)
@@ -134,6 +158,7 @@ static void __aio_unref_queue(struct aio_queue *q)
 	 * may arrive since we cannot free the queue object without first
 	 * taking the maplock, which requires releasing the queue lock. */
 	pthread_mutex_unlock(&q->lock);
+	LOCK(map_update_lock);
 	pthread_rwlock_wrlock(&maplock);
 	pthread_mutex_lock(&q->lock);
 	if (q->ref == 1) {
@@ -144,11 +169,13 @@ static void __aio_unref_queue(struct aio_queue *q)
 		a_dec(&aio_fd_cnt);
 		pthread_rwlock_unlock(&maplock);
 		pthread_mutex_unlock(&q->lock);
+		UNLOCK(map_update_lock);
 		free(q);
 	} else {
 		q->ref--;
 		pthread_rwlock_unlock(&maplock);
 		pthread_mutex_unlock(&q->lock);
+		UNLOCK(map_update_lock);
 	}
 }