diff --git a/src/lib9/open.c b/src/lib9/open.c
index 896ca52..e76aabe 100644
--- a/src/lib9/open.c
+++ b/src/lib9/open.c
@@ -28,6 +28,10 @@
 		umode |= O_DIRECT;
 		mode ^= ODIRECT;
 	}
+	if(mode&ONONBLOCK){
+		umode |= O_NONBLOCK;
+		mode ^= ONONBLOCK;
+	}
 	if(mode){
 		werrstr("mode 0x%x not supported", mode);
 		return -1;