diff --git a/src/chunk.lua b/src/chunk.lua
index 3839d9d..294d57b 100644
--- a/src/chunk.lua
+++ b/src/chunk.lua
@@ -58,6 +58,7 @@ function Chunk:load(thread)
   -- each vertex is currently 36 bytes
   self.verticesData = love.data.newByteData(maxVertices * 36)
 
+  -- add 1 to the size to include the border
   local blocks = {}
   for i = 0, CHUNK_SIZE + 1 do
     blocks[i] = {}
@@ -77,11 +78,9 @@ function Chunk:getBlock(x, y, z)
   if y < 1 or y > CHUNK_HEIGHT then return 0 end
 
   -- translate to local coordinates
-  x = x - self.position.x
-  y = y - self.position.y
-  z = z - self.position.z
+  local i, j, k = x - self.position.x, y - self.position.y, z - self.position.z
 
-  return self.blocks[x][y][z]
+  return self.blocks[i][j][k]
 end
 
 function Chunk:setBlock(x, y, z, block)
@@ -95,6 +94,23 @@ function Chunk:setBlock(x, y, z, block)
   self.blocks[i][j][k] = block
 
   self.dirty = true
+
+  -- if border block, mark adjacent chunks as dirty
+  local adjacentX, adjacentZ
+  if i == 1 then
+    adjacentX = self.world:getChunk(x - 1, z)
+  elseif i == CHUNK_SIZE then
+    adjacentX = self.world:getChunk(x + 1, z)
+  end
+
+  if k == 1 then
+    adjacentZ = self.world:getChunk(x, z - 1)
+  elseif k == CHUNK_SIZE then
+    adjacentZ = self.world:getChunk(x, z + 1)
+  end
+
+  if adjacentX then adjacentX.dirty = true end
+  if adjacentZ then adjacentZ.dirty = true end
 end
 
 function Chunk:update()
diff --git a/src/player.lua b/src/player.lua
index 9fc9dad..f8acd3d 100644
--- a/src/player.lua
+++ b/src/player.lua
@@ -69,12 +69,6 @@ end
 function Player:draw()
   self.camera:draw()
 
-  if self.nextBlock then
-    local x, y, z = self.nextBlock:unpack()
-    local block = self.world:getBlock(x, y, z)
-    debug("light", block)
-  end
-
   if self.currentBlock then
     local x, y, z = self.currentBlock:unpack()
     local chunk = self.world:getChunk(x, z)
diff --git a/src/world.lua b/src/world.lua
index 75428cc..cde27b9 100644
--- a/src/world.lua
+++ b/src/world.lua
@@ -11,9 +11,11 @@ function World:new()
 
   -- self:load()
 
-  self._generated = false
+  self.threads = {}
 
-  self.thread = love.thread.newThread("src/load_mesh.lua")
+  for i = 1, 4 do
+    self.threads[i] = love.thread.newThread("src/load_mesh.lua")
+  end
 
   self:loadChunk(0, 0)
 
@@ -31,6 +33,16 @@ function World:save()
   bitser.dumpLoveFile("world.dat", chunks)
 end
 
+function World:getThread()
+  for _, thread in pairs(self.threads) do
+    if thread:isRunning() == false then
+      return thread
+    end
+  end
+
+  return nil
+end
+
 function World:load()
   local chunks = bitser.loadLoveFile("world.dat")
 
@@ -46,11 +58,6 @@ function World:load()
 end
 
 function World:generateChunk(wx, wz)
-  if self._generated then return end
-
-  -- only allow one chunk to be generated at a time
-  self._generated = true
-
   local x = math.floor((wx-1) / CHUNK_SIZE)
   local z = math.floor((wz-1) / CHUNK_SIZE)
 
@@ -108,21 +115,22 @@ function World:loadChunk(x, z)
 
   if chunk then
     chunk.loaded = true
-
-    if chunk.dirty and not self.thread:isRunning() then
-      chunk:load(self.thread)
-    end
   else
     self:generateChunk(x, z)
   end
 end
 
 function World:update(dt)
-  self._generated = false
-
   for i, v in pairs(self.chunks) do
     for j, chunk in pairs(v) do
       if chunk.loaded then
+
+        if chunk.dirty then
+          local thread = self:getThread()
+
+          if thread then chunk:load(thread) end
+        end
+
         chunk:update(dt)
       end