diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index d06dcc399069..10bcec2dd49d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -472,13 +472,12 @@ static int proc_get_long(char **buf, size_t *size,
 			  unsigned long *val, bool *neg,
 			  const char *perm_tr, unsigned perm_tr_len, char *tr)
 {
-	int len;
 	char *p, tmp[TMPBUFLEN];
+	ssize_t len = *size;
 
-	if (!*size)
+	if (len <= 0)
 		return -EINVAL;
 
-	len = *size;
 	if (len > TMPBUFLEN - 1)
 		len = TMPBUFLEN - 1;