diff --git a/src/checks.c b/src/checks.c
index b0de77088..78d4e390b 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -1625,7 +1625,8 @@ static int connect_conn_chk(struct task *t)
 	clear_addr(&conn->addr.from);
 
 	conn_prepare(conn, proto, check->xprt);
-	conn_install_mux(conn, &mux_pt_ops, cs, s->proxy, NULL);
+	if (conn_install_mux(conn, &mux_pt_ops, cs, s->proxy, NULL) < 0)
+		return SF_ERR_RESOURCE;
 	cs_attach(cs, check, &check_conn_cb);
 
 	/* only plain tcp-check supports quick ACK */
@@ -2818,7 +2819,8 @@ static int tcpcheck_main(struct check *check)
 			}
 
 			conn_prepare(conn, proto, xprt);
-			conn_install_mux(conn, &mux_pt_ops, cs, proxy, NULL);
+			if (conn_install_mux(conn, &mux_pt_ops, cs, proxy, NULL) < 0)
+				return SF_ERR_RESOURCE;
 			cs_attach(cs, check, &check_conn_cb);
 
 			ret = SF_ERR_INTERNAL;