1 files changed, 2 insertions, 0 deletions
diff --git a/perlio.h b/perlio.h
index 32a01133f8..8cb4f7ed06 100644
--- a/perlio.h
+++ b/perlio.h
@@ -312,4 +312,6 @@ extern int	PerlIO_isutf8		(PerlIO *);
 extern int	PerlIO_apply_layers	(pTHX_ PerlIO *f,const char *mode, const char *names);
 #endif
 
+extern void PerlIO_debug(const char *fmt,...);
+
 #endif /* _PERLIO_H */