diff --git a/nselib/dns.lua b/nselib/dns.lua
index 9f4f95668..c0acf4f57 100644
--- a/nselib/dns.lua
+++ b/nselib/dns.lua
@@ -1406,7 +1406,6 @@ end
 --        <code>mask</code>    - byte containing the length of the subnet mask
 --        <code>address</code> - string containing the IP address
 function addClientSubnet(pkt,Z,subnet)
-  local udp_payload_size = 4096
   local code = 8 -- https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-11
   local scope_mask = 0 -- In requests, it MUST be set to 0 see draft
   local data = bin.pack(">SCCA",subnet.family or 1,subnet.mask,scope_mask,ipOps.ip_to_str(subnet.address))
@@ -1419,7 +1418,6 @@ end
 -- @param pkt Table representing DNS packet.
 -- @param Z Table of Z flags. Only DO is supported.
 function addNSID (pkt,Z)
-  local udp_payload_size = 4096
   local opt = bin.pack(">SS",3, 0) -- nsid data
   addOPT(pkt,Z,opt)
 end