diff --git a/leaderboard.lua b/leaderboard.lua
index 582769c..bb49758 100644
--- a/leaderboard.lua
+++ b/leaderboard.lua
@@ -395,8 +395,6 @@ local function mapNotExists(player, map)
 	CONS_Printf(player, string.format("Map doesn't exist: %s", map:upper()))
 end
 
-local ALPH = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
-
 local function changelevel(player, ...)
 	if not doyoudare(player) then
 		return
@@ -418,6 +416,8 @@ local function changelevel(player, ...)
 	end
 
 	local mapnum = 0
+	local A = string.byte("A")
+
 	if tonumber(p) != nil then
 		-- Non extended map numbers
 		if tonumber(q) == nil then
@@ -427,11 +427,12 @@ local function changelevel(player, ...)
 		mapnum = tonumber(p) * 10 + tonumber(q)
 	else
 		--Extended map numbers
-		p = ALPH:find(p) - 1
+		p = string.byte(p) - A
 		local qn = tonumber(q)
 		if qn == nil then
-			qn = ALPH:find(q) + 9
+			qn = string.byte(q) - A + 10
 		end
+
 		mapnum = 36 * p + qn + 100
 	end