diff --git a/uloop.c b/uloop.c
index ec37925..a263a01 100644
--- a/uloop.c
+++ b/uloop.c
@@ -236,7 +236,7 @@ int uloop_fd_add(struct uloop_fd *sock, unsigned int flags)
 	unsigned int fl;
 	int ret;
 
-	if (!sock->registered) {
+	if (!sock->registered && !(flags & ULOOP_BLOCKING)) {
 		fl = fcntl(sock->fd, F_GETFL, 0);
 		fl |= O_NONBLOCK;
 		fcntl(sock->fd, F_SETFL, fl);
diff --git a/uloop.h b/uloop.h
index 35ee3a5..10a117f 100644
--- a/uloop.h
+++ b/uloop.h
@@ -39,6 +39,7 @@ typedef void (*uloop_timeout_handler)(struct uloop_timeout *t);
 #define ULOOP_READ		(1 << 0)
 #define ULOOP_WRITE		(1 << 1)
 #define ULOOP_EDGE_TRIGGER	(1 << 2)
+#define ULOOP_BLOCKING		(1 << 3)
 
 struct uloop_fd
 {