diff --git a/include/stdio.h b/include/stdio.h
index 41ae893dd7d..97e8144372f 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -294,14 +294,16 @@ int	 vprintf(const char * __restrict, __va_list);
 int	 vsprintf(char * __restrict, const char * __restrict,
 	    __va_list);
 
-#if __ISO_C_VISIBLE >= 1999
+#if __ISO_C_VISIBLE >= 1999 || __POSIX_VISIBLE >= 199506
 int	 snprintf(char * __restrict, size_t, const char * __restrict,
 	    ...) __printflike(3, 4);
+int	 vsnprintf(char * __restrict, size_t, const char * __restrict,
+	    __va_list) __printflike(3, 0);
+#endif
+#if __ISO_C_VISIBLE >= 1999
 int	 vfscanf(FILE * __restrict, const char * __restrict, __va_list)
 	    __scanflike(2, 0);
 int	 vscanf(const char * __restrict, __va_list) __scanflike(1, 0);
-int	 vsnprintf(char * __restrict, size_t, const char * __restrict,
-	    __va_list) __printflike(3, 0);
 int	 vsscanf(const char * __restrict, const char * __restrict, __va_list)
 	    __scanflike(2, 0);
 #endif