diff --git a/vdiscover/data/prototypes.conf b/vdiscover/data/prototypes.conf
index 29606d2..941d2e0 100644
--- a/vdiscover/data/prototypes.conf
+++ b/vdiscover/data/prototypes.conf
@@ -110,7 +110,7 @@ int bfd_check_format(addr,int);
 ; ctype.h
 char tolower(char);
 char toupper(char);
-addr __ctype_b_loc(void);
+;addr __ctype_b_loc(void);
 addr __ctype_tolower_loc(void);
 addr __ctype_toupper_loc(void);