1 files changed, 1 insertions, 0 deletions
diff --git a/rubyio.h b/rubyio.h
index 44f679494e..3fe3282190 100644
--- a/rubyio.h
+++ b/rubyio.h
@@ -63,6 +63,7 @@ int rb_getc _((FILE*));
 long rb_io_fread _((char *, long, FILE *));
 long rb_io_fwrite _((const char *, long, FILE *));
 int  rb_io_mode_flags _((const char*));
+int  rb_io_modenum_flags _((int));
 void rb_io_check_writable _((OpenFile*));
 void rb_io_check_readable _((OpenFile*));
 void rb_io_fptr_finalize _((OpenFile*));