--- gbser_posix.cc.orig	Thu May  2 17:26:47 2019
+++ gbser_posix.cc	Sat Aug 24 19:55:42 2019
@@ -142,7 +142,7 @@ void* gbser_init(const char* port_name)
   if (0 == strcmp(port_name, "-")) {
     h->fd = 0;
     return h;
-  } else if (h->fd = open(port_name, O_RDWR | O_NOCTTY), h->fd == -1) {
+  } else if (h->fd = open(port_name, O_RDWR | O_NOCTTY | O_NDELAY), h->fd == -1) {
     warning("Failed to open port (%s)\n", strerror(errno));
     goto failed;
   }
