diff --git a/newlib/libc/include/ctype.h b/newlib/libc/include/ctype.h
index 8b1013ac0..932a567e2 100644
--- a/newlib/libc/include/ctype.h
+++ b/newlib/libc/include/ctype.h
@@ -111,7 +111,7 @@ const char *__locale_ctype_ptr (void);
 #ifdef __HAVE_LOCALE_INFO__
 const char *__locale_ctype_ptr_l (locale_t);
 #else
-static __inline char *
+static __inline const char *
 __locale_ctype_ptr_l(locale_t _l)
 {
 	(void)_l;