diff --git a/bundle/main.lua b/bundle/main.lua
index 140c697..1285376 100644
--- a/bundle/main.lua
+++ b/bundle/main.lua
@@ -1,12 +1,12 @@
-spread_probability = 0.6
+local spread_probability = 0.6
 
-display_inputinfo_counter = 0
-display_probability_counter = 1
+local display_inputinfo_counter = 0
+local display_probability_counter = 1
 
-tiles = {}
-tiletypes = {unknown = 0, empty = 1, wall = 2}
+local tiles = {}
+local tiletypes = {unknown = 0, empty = 1, wall = 2}
 
-queue = {}
+local queue = {}
 
 function initializeTiles()
 	tiles = {}