--- Libc/Libc-1669.40.2/include/secure/_stdio.h
+++ Libc/Libc-1698.100.8/include/secure/_stdio.h
@@ -28,7 +28,10 @@
 #ifndef _SECURE__STDIO_H_
 #define _SECURE__STDIO_H_
 
+#include <_bounds.h>
 #include <secure/_common.h>
+
+_LIBC_SINGLE_BY_DEFAULT()
 
 #if _USE_FORTIFY_LEVEL > 0
 
@@ -40,7 +43,7 @@
 #ifndef UNIFDEF_DRIVERKIT
 /* sprintf, vsprintf, snprintf, vsnprintf */
 #if __has_builtin(__builtin___sprintf_chk) || defined(__GNUC__)
-extern int __sprintf_chk (char * __restrict, int, size_t,
+extern int __sprintf_chk (char * __restrict _LIBC_UNSAFE_INDEXABLE, int, size_t,
 			  const char * __restrict, ...);
 
 #undef sprintf
@@ -51,7 +54,7 @@
 
 #if __DARWIN_C_LEVEL >= 200112L
 #if __has_builtin(__builtin___snprintf_chk) || defined(__GNUC__)
-extern int __snprintf_chk (char * __restrict, size_t, int, size_t,
+extern int __snprintf_chk (char * __restrict _LIBC_COUNT(__maxlen), size_t __maxlen, int, size_t,
 			   const char * __restrict, ...);
 
 #undef snprintf
@@ -61,7 +64,7 @@
 
 #ifndef UNIFDEF_DRIVERKIT
 #if __has_builtin(__builtin___vsprintf_chk) || defined(__GNUC__)
-extern int __vsprintf_chk (char * __restrict, int, size_t,
+extern int __vsprintf_chk (char * __restrict _LIBC_UNSAFE_INDEXABLE, int, size_t,
 			   const char * __restrict, va_list);
 
 #undef vsprintf
@@ -71,7 +74,7 @@
 #endif /* UNIFDEF_DRIVERKIT */
 
 #if __has_builtin(__builtin___vsnprintf_chk) || defined(__GNUC__)
-extern int __vsnprintf_chk (char * __restrict, size_t, int, size_t,
+extern int __vsnprintf_chk (char * __restrict _LIBC_COUNT(__maxlen), size_t __maxlen, int, size_t,
 			    const char * __restrict, va_list);
 
 #undef vsnprintf