1 files changed, 1 insertions, 0 deletions
diff --git a/handy.h b/handy.h
index 32239b9ee3..d488922a44 100644
--- a/handy.h
+++ b/handy.h
@@ -57,6 +57,7 @@ Null SV pointer. (No longer available when C<PERL_CORE> is defined.)
 #define MUTABLE_AV(p)	((AV *)MUTABLE_PTR(p))
 #define MUTABLE_CV(p)	((CV *)MUTABLE_PTR(p))
 #define MUTABLE_HV(p)	((HV *)MUTABLE_PTR(p))
+#define MUTABLE_IO(p)	((IO *)MUTABLE_PTR(p))
 #define MUTABLE_SV(p)	((SV *)MUTABLE_PTR(p))
 
 /* XXX Configure ought to have a test for a boolean type, if I can