diff --git a/security/tomoyo/audit.c b/security/tomoyo/audit.c
index 023bedd9dfa3..7cf8fdbb29bf 100644
--- a/security/tomoyo/audit.c
+++ b/security/tomoyo/audit.c
@@ -423,7 +423,7 @@ void tomoyo_write_log(struct tomoyo_request_info *r, const char *fmt, ...)
 	int len;
 
 	va_start(args, fmt);
-	len = vsnprintf((char *) &len, 1, fmt, args) + 1;
+	len = vsnprintf(NULL, 0, fmt, args) + 1;
 	va_end(args);
 	va_start(args, fmt);
 	tomoyo_write_log2(r, len, fmt, args);
diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index ff17abc96e5c..f4cd9b58b205 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -2057,7 +2057,7 @@ int tomoyo_supervisor(struct tomoyo_request_info *r, const char *fmt, ...)
 	bool quota_exceeded = false;
 
 	va_start(args, fmt);
-	len = vsnprintf((char *) &len, 1, fmt, args) + 1;
+	len = vsnprintf(NULL, 0, fmt, args) + 1;
 	va_end(args);
 	/* Write /sys/kernel/security/tomoyo/audit. */
 	va_start(args, fmt);