diff --git a/CHANGELOG b/CHANGELOG
index b2c8c8009..9a8dfe06b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -32,6 +32,9 @@ o [NSE][GH#2174] Script hostmap-crtsh got improved in several ways. The most
   identities that are syntactically incorrect to be hostnames are now ignored.
   [Michel Le Bihan, nnposter]
 
+o [NSE][GH#2197] Client packets composed by the DHCP library will now contain
+  option 51 (IP address lease time) only when requested. [nnposter]
+
 o [NSE][GH#2192] XML decoding in library citrixxml no longer crashes when
   encountering a character reference with codepoint greater than 255. (These
   references are now left unmodified.) [nnposter]
diff --git a/nselib/dhcp.lua b/nselib/dhcp.lua
index ac7949b0d..e1b21d1c3 100644
--- a/nselib/dhcp.lua
+++ b/nselib/dhcp.lua
@@ -396,7 +396,7 @@ end
 --@param overrides       [optional] A table of overrides. If a field in the table matches a field in the DHCP
 --                       packet (see rfc2131 section 2 for a list of possible fields), the value in the table
 --                       will be sent instead of the default value.
---@param lease_time      [optional] The lease time used when requestint an IP. Default: 1 second.
+--@param lease_time      [optional] The lease time used when requesting an IP. Default: none.
 --@param transaction_id  The identity of the transaction.
 --
 --@return status (true or false)
@@ -444,7 +444,9 @@ function dhcp_build(request_type, ip_address, mac_address, options, request_opti
   end
 
   packet = packet .. string.pack(">Bs1", 0x37, request_options) -- Request options
-  packet = packet .. string.pack(">BBI4", 0x33, 4, lease_time or 1) -- Lease time
+  if lease_time then
+    packet = packet .. string.pack(">BBI4", 0x33, 4, lease_time) -- Lease time
+  end
 
   packet = packet .. "\xFF" -- Termination
 
@@ -599,7 +601,7 @@ end
 --@param overrides       [optional] A table of overrides. If a field in the table matches a field in the DHCP
 --                       packet (see rfc2131 section 2 for a list of possible fields), the value in the table
 --                       will be sent instead of the default value.
---@param lease_time      [optional] The lease time used when requestint an IP. Default: 1 second.
+--@param lease_time      [optional] The lease time used when requesting an IP. Default: none.
 --@return status (true or false)
 --@return The parsed response, as a table.
 function make_request(target, request_type, ip_address, mac_address, options, request_options, overrides, lease_time)