1 files changed, 1 insertions, 0 deletions
diff --git a/io.c b/io.c
index 54c3dee767..24fad23a41 100644
--- a/io.c
+++ b/io.c
@@ -3748,6 +3748,7 @@ rb_io_initialize(argc, argv, io)
     else {
 #if defined(HAVE_FCNTL) && defined(F_GETFL)
 	flags = fcntl(fd, F_GETFL);
+	if (flags == -1) rb_sys_fail(0);
 #else
 	flags = O_RDONLY;
 #endif