diff --git a/ticketmachine.lua b/ticketmachine.lua
index 18c3cfa..64e49b4 100644
--- a/ticketmachine.lua
+++ b/ticketmachine.lua
@@ -541,9 +541,15 @@ local function buildFinalCardData(payload, respData)
   }
 end
 
+local function generateNumericCode(prefix, digits)
+  local width = math.max(1, math.floor(tonumber(digits) or 1))
+  local maxValue = (10 ^ width) - 1
+  local num = string.format('%0' .. tostring(width) .. 'd', math.random(0, maxValue))
+  return tostring(prefix or 'ID'):upper() .. '-' .. num
+end
+
 local function generateCardId()
-  local num = string.format('%06d', math.random(0, 999999))
-  return 'IC-' .. num
+  return generateNumericCode('IC', 6)
 end
 
 local function issueTicketFromPeripheral(fromNameEnArg, toNameEnArg, apiType, rides, cost, startStationArg, terminalStationArg, fromNameCnUArg, toNameCnUArg, fallbackTicketId)
@@ -2002,12 +2008,7 @@ local function showPrePrintCheck()
 end
 
 local function generateTicketId()
-  local function randLetter()
-    return string.char(string.byte('A') + math.random(0, 25))
-  end
-  local prefix = randLetter() .. randLetter()
-  local num = string.format('%08d', math.random(0, 99999999))
-  return prefix .. '-' .. num
+  return generateNumericCode('TK', 8)
 end
 
 local function ensureTicketIdFormat(id)