diff -r f3a458479f9c -r ce671935f504 plugins/xkcd2.lua
--- a/plugins/xkcd2.lua	Thu Jul 09 14:38:17 2015 +0200
+++ b/plugins/xkcd2.lua	Thu Jul 09 14:38:47 2015 +0200
@@ -21,7 +21,7 @@
 			if t ~= '"' then
 				num = tonumber(num);
 				if num and num < 0 then
-					num = #strip + num;
+					num = table.maxn(strips) + num;
 				end
 			end
 			strip = strips[num or q:lower()];