diff --git a/helpers.lua b/helpers.lua
index d00f430..d4cafd3 100644
--- a/helpers.lua
+++ b/helpers.lua
@@ -1,11 +1,11 @@
-function ham_radio.validate_frequency(frequency)
+function ham_radio.validate_frequency(frequency, is_receiver)
   if frequency == "" then
     return true -- empty frequency is allowed to disable transmitter/receiver
   end
   local transmission_is_allowed = true
   local num_freq = tonumber(frequency)
   local freq = tostring(num_freq)
-  if next(ham_radio.find_transmitters(frequency)) then
+  if is_receiver ~= nil and next(ham_radio.find_transmitters(frequency)) then
     if num_freq >= ham_radio.settings.locked_frequency.min
     and num_freq <= ham_radio.settings.locked_frequency.max then
       -- transmitter is in locked frequency range
diff --git a/receiver.lua b/receiver.lua
index 074740c..c4531f1 100644
--- a/receiver.lua
+++ b/receiver.lua
@@ -37,7 +37,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
   if formname ~= "ham_radio:configure_handheld_receiver" or not minetest.is_player(player) then
     return false
   end
-  if not ham_radio.validate_frequency(fields.frequency) then
+  if not ham_radio.validate_frequency(fields.frequency, true) then
     return false
   end
   local item = player:get_wielded_item()