diff --git a/src/pty.c b/src/pty.c
index e5d47ed..b046a6a 100644
--- a/src/pty.c
+++ b/src/pty.c
@@ -470,7 +470,7 @@ int pty_spawn(pty_process *process, pty_read_cb read_cb, pty_exit_cb exit_cb) {
     status = -errno;
     goto error;
   }
-  if (fcntl(master, F_SETFD, flags | O_NONBLOCK) == -1) {
+  if (fcntl(master, F_SETFL, flags | O_NONBLOCK) == -1) {
     status = -errno;
     goto error;
   }
@@ -502,4 +502,4 @@ error:
   waitpid(pid, NULL, 0);
   return status;
 }
-#endif
\ No newline at end of file
+#endif