diff --git a/.luacheckrc b/.luacheckrc
new file mode 100644
index 0000000..e4991d5
--- /dev/null
+++ b/.luacheckrc
@@ -0,0 +1,19 @@
+
+globals = {
+	"lightning"
+}
+
+read_globals = {
+	-- Stdlib
+	string = {fields = {"split"}},
+	table = {fields = {"copy", "getn"}},
+	"PcgRandom",
+
+	-- Minetest
+	"minetest",
+	"vector", "ItemStack",
+	"dump",
+
+	-- mods
+	"default", "fire"
+}
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..1fb315e
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,11 @@
+language: generic
+addons:
+  apt:
+    packages:
+    - luarocks
+before_install:
+  - luarocks install --local luacheck
+script:
+- $HOME/.luarocks/bin/luacheck ./
+notifications:
+  email: false
diff --git a/depends.txt b/depends.txt
deleted file mode 100644
index 09060cc..0000000
--- a/depends.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-default?
-fire?
diff --git a/description.txt b/description.txt
deleted file mode 100644
index 98fdb36..0000000
--- a/description.txt
+++ /dev/null
@@ -1 +0,0 @@
-A mod that adds thunder and lightning effects.
diff --git a/init.lua b/init.lua
index 3ed0c3a..59198fd 100644
--- a/init.lua
+++ b/init.lua
@@ -19,9 +19,12 @@ lightning.range_v = 50
 lightning.size = 100
 -- disable this to stop lightning mod from striking
 lightning.auto = true
+-- range of the skybox highlight and sound effect
+lightning.effect_range = 500
 
 local rng = PcgRandom(32321123312123)
 
+-- table with playername as key and previous skybox as value
 local ps = {}
 local ttl = 1
 
@@ -34,9 +37,12 @@ local revertsky = function()
 		return
 	end
 
-	for key, entry in pairs(ps) do
-		local sky = entry.sky
-		entry.p:set_sky(sky.bgcolor, sky.type, sky.textures)
+	for playername, sky in pairs(ps) do
+		local player = minetest.get_player_by_name(playername)
+		-- check if the player is still online
+		if player then
+			player:set_sky(sky.bgcolor, sky.type, sky.textures)
+		end
 	end
 
 	ps = {}
@@ -57,7 +63,7 @@ local function choose_pos(pos)
 
 		local r = rng:next(1, playercount)
 		local randomplayer = playerlist[r]
-		pos = randomplayer:getpos()
+		pos = randomplayer:get_pos()
 
 		-- avoid striking underground
 		if pos.y < -20 then
@@ -123,7 +129,7 @@ lightning.strike = function(pos)
 		glow = 14,
 	})
 
-	minetest.sound_play({ pos = pos, name = "lightning_thunder", gain = 10, max_hear_distance = 500 })
+	minetest.sound_play({ pos = pos, name = "lightning_thunder", gain = 10, max_hear_distance = lightning.effect_range })
 
 	-- damage nearby objects, player or not
 	for _, obj in ipairs(minetest.get_objects_inside_radius(pos, 5)) do
@@ -134,14 +140,18 @@ lightning.strike = function(pos)
 	local playerlist = minetest.get_connected_players()
 	for i = 1, #playerlist do
 		local player = playerlist[i]
-		local sky = {}
+		local distance = vector.distance(player:get_pos(), pos)
 
-		sky.bgcolor, sky.type, sky.textures = player:get_sky()
+		-- only affect players inside effect_range
+		if distance < lightning.effect_range then
+			local sky = {}
+			sky.bgcolor, sky.type, sky.textures = player:get_sky()
 
-		local name = player:get_player_name()
-		if ps[name] == nil then
-			ps[name] = {p = player, sky = sky}
-			player:set_sky(0xffffff, "plain", {})
+			local name = player:get_player_name()
+			if ps[name] == nil then
+				ps[name] = sky
+				player:set_sky(0xffffff, "plain", {})
+			end
 		end
 	end
 
@@ -217,7 +227,7 @@ minetest.register_node("lightning:dying_flame", {
 })
 
 -- if other mods disable auto lightning during initialization, don't trigger the first lightning.
-minetest.after(5, function(dtime)
+minetest.after(5, function()
 	if lightning.auto then
 		minetest.after(rng:next(lightning.interval_low,
 			lightning.interval_high), lightning.strike)
diff --git a/mod.conf b/mod.conf
index 948a407..1b5815a 100644
--- a/mod.conf
+++ b/mod.conf
@@ -1 +1,3 @@
 name = lightning
+optional_depends = default, fire
+description = A mod that adds thunder and lightning effects.
\ No newline at end of file