diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 696eb39fc1cb44978c27b47d20775eb2ceac4ba8..a7e42f9a405c1c6fde97fc3cc34628a45016b03c 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -51,9 +51,7 @@ static int param_set_hashtbl_sz(const char *val, const struct kernel_param *kp)
 	ret = kstrtoul(val, 0, &num);
 	if (ret == -EINVAL)
 		goto out_inval;
-	nbits = fls(num);
-	if (num > (1U << nbits))
-		nbits++;
+	nbits = fls(num - 1);
 	if (nbits > MAX_HASHTABLE_BITS || nbits < 2)
 		goto out_inval;
 	*(unsigned int *)kp->arg = nbits;