diff --git a/src/haproxy.c b/src/haproxy.c
index bd8608f..eb5e65b 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1780,6 +1780,11 @@
 	global.hardmaxconn = global.maxconn;  /* keep this max value */
 	global.maxsock += global.maxconn * 2; /* each connection needs two sockets */
 	global.maxsock += global.maxpipes * 2; /* each pipe needs two FDs */
+	/* compute fd used by async engines */
+	if (global.ssl_used_async_engines) {
+		int sides = !!global.ssl_used_frontend + !!global.ssl_used_backend;
+		global.maxsock += global.maxconn * sides * global.ssl_used_async_engines;
+	}
 
 	if (global.stats_fe)
 		global.maxsock += global.stats_fe->maxconn;
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index 4741be1..f9d5f25 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -161,6 +161,7 @@
 int sslconns = 0;
 int totalsslconns = 0;
 static struct xprt_ops ssl_sock;
+int nb_engines = 0;
 
 static struct {
 	char *crt_base;             /* base directory path for certificates */
@@ -411,6 +412,9 @@
 	el = calloc(1, sizeof(*el));
 	el->e = engine;
 	LIST_ADD(&openssl_engines, &el->list);
+	nb_engines++;
+	if (global_ssl.async)
+		global.ssl_used_async_engines = nb_engines;
 	return 0;
 
 fail_set_method:
@@ -7978,6 +7982,7 @@
 {
 #if (OPENSSL_VERSION_NUMBER >= 0x1010000fL) && !defined(OPENSSL_NO_ASYNC)
 	global_ssl.async = 1;
+	global.ssl_used_async_engines = nb_engines;
 	return 0;
 #else
 	memprintf(err, "'%s': openssl library does not support async mode", args[0]);