1 files changed, 1 insertions, 1 deletions
diff --git a/io.c b/io.c
index 4e7df04301..56e2b6361c 100644
--- a/io.c
+++ b/io.c
@@ -2883,7 +2883,7 @@ rb_io_ctl(io, req, arg, io_p)
 	narg = 1;
     }
     else {
-	Check_Type(arg, T_STRING);
+	arg = rb_str_to_str(arg);
 
 #ifdef IOCPARM_MASK
 #ifndef IOCPARM_LEN