1 files changed, 1 insertions, 0 deletions
diff --git a/rubyio.h b/rubyio.h
index 80ad45932e..377a66b719 100644
--- a/rubyio.h
+++ b/rubyio.h
@@ -32,6 +32,7 @@ typedef struct OpenFile {
 #define FMODE_BINMODE   4
 #define FMODE_SYNC      8
 #define FMODE_WBUF     16
+#define FMODE_RBUF     32
 
 #define GetOpenFile(obj,fp) rb_io_check_closed((fp) = RFILE(rb_io_taint_check(obj))->fptr)