diff --git a/overviewer_core/quadtree.py b/overviewer_core/quadtree.py
index 200f998..7725ae1 100644
--- a/overviewer_core/quadtree.py
+++ b/overviewer_core/quadtree.py
@@ -13,30 +13,23 @@
 #    You should have received a copy of the GNU General Public License along
 #    with the Overviewer.  If not, see <http://www.gnu.org/licenses/>.
 
-import multiprocessing
 import itertools
 import os
 import os.path
 import functools
 import re
 import shutil
-import collections
-import json
 import logging
-import cPickle
 import stat
 import errno 
 import time
 import random
-from time import gmtime, strftime, sleep
 
 from PIL import Image
 
-from . import nbt
 from . import chunk
 from .optimizeimages import optimize_image
 from c_overviewer import get_render_mode_inheritance
-import composite
 
 
 """
diff --git a/overviewer_core/rendernode.py b/overviewer_core/rendernode.py
index f4c2f67..315f602 100644
--- a/overviewer_core/rendernode.py
+++ b/overviewer_core/rendernode.py
@@ -69,10 +69,10 @@ def pool_initializer(rendernode):
         c_overviewer.set_render_mode_options(mode, rendernode.options.rendermode_options[mode])
     
     # load biome data in each process, if needed
-    for quadtree in rendernode.quadtrees:
-        if quadtree.world.useBiomeData:
+    for qtree in rendernode.quadtrees:
+        if qtree.world.useBiomeData:
             # make sure we've at least *tried* to load the color arrays in this process...
-            textures.prepareBiomeData(quadtree.world.worlddir)
+            textures.prepareBiomeData(qtree.world.worlddir)
             if not textures.grasscolor or not textures.foliagecolor:
                 raise Exception("Can't find grasscolor.png or foliagecolor.png")
             # only load biome data once