diff --git a/overviewer_core/quadtree.py b/overviewer_core/quadtree.py
index 17209aa..c24e43d 100644
--- a/overviewer_core/quadtree.py
+++ b/overviewer_core/quadtree.py
@@ -270,7 +270,7 @@ class QuadtreeGen(object):
                     
         return chunklist   
         
-    def get_uppertiles(self,zoom):
+    def get_compositetiles(self,zoom):
         """Returns the inner tiles at the given zoom level that need to be rendered
 
         """    
@@ -282,7 +282,7 @@ class QuadtreeGen(object):
   
             yield [self,tilepath, name]
     
-    def render_uppertile(self, dest, name):
+    def render_compositetile(self, dest, name):
         """
         Renders a tile at os.path.join(dest, name)+".ext" by taking tiles from
         os.path.join(dest, name, "{0,1,2,3}.png")
@@ -337,7 +337,7 @@ class QuadtreeGen(object):
         # quit now if we don't need rerender
         if not needs_rerender:
             return    
-        #logging.debug("writing out uppertile {0}".format(imgpath))
+        #logging.debug("writing out compositetile {0}".format(imgpath))
 
         # Create the actual image now
         img = Image.new("RGBA", (384, 384), self.bgcolor)
@@ -825,7 +825,7 @@ class Tile(object):
     """A simple container class that represents a single render-tile.
 
     A render-tile is a tile that is rendered, not a tile composed of other
-    tiles (upper-tile).
+    tiles (composite-tile).
 
     """
     __slots__ = ("col", "row", "path")
diff --git a/overviewer_core/rendernode.py b/overviewer_core/rendernode.py
index d41362a..5c2dbc4 100644
--- a/overviewer_core/rendernode.py
+++ b/overviewer_core/rendernode.py
@@ -353,13 +353,13 @@ class RenderNode(object):
             
             self.print_statusline(0, total, level, True)
 
-            # Same deal as above. _apply_render_uppertile adds tiles in batch
+            # Same deal as above. _apply_render_compositetile adds tiles in batch
             # to the worker pool and yields result objects that return the
             # number of tiles rendered.
             #
             # XXX Some quadtrees may not have tiles at this zoom level if we're
             # not assuming they all have the same depth!!
-            for result in self._apply_render_uppertile(pool, zoom,batch_size):
+            for result in self._apply_render_compositetile(pool, zoom,batch_size):
                 results.append(result)
                 # every second drain some of the queue
                 timestamp2 = time.time()
@@ -389,7 +389,7 @@ class RenderNode(object):
 
         # Do the final one right here:
         for q in quadtrees:
-            q.render_uppertile(os.path.join(q.destdir, q.tiledir), "base")
+            q.render_compositetile(os.path.join(q.destdir, q.tiledir), "base")
 
     def _get_dirty_tiles(self, procs):
         """Returns two items:
@@ -489,8 +489,8 @@ class RenderNode(object):
         if len(batch):
             yield pool.apply_async(func=render_worldtile_batch, args= [batch])
 
-    def _apply_render_uppertile(self, pool, zoom,batch_size):
-        """Same as _apply_render_worltiles but for the uppertile routine.
+    def _apply_render_compositetile(self, pool, zoom,batch_size):
+        """Same as _apply_render_worltiles but for the compositetile routine.
         Returns an iterator that yields result objects from tasks that have
         been applied to the pool.
         """
@@ -500,7 +500,7 @@ class RenderNode(object):
         batch = []
         jobcount = 0
         # roundrobin add tiles to a batch job (thus they should all roughly work on similar chunks)
-        iterables = [q.get_uppertiles(zoom) for q in self.quadtrees if zoom <= q.p]
+        iterables = [q.get_compositetiles(zoom) for q in self.quadtrees if zoom <= q.p]
         for job in util.roundrobin(iterables):
             # fixup so the worker knows which quadtree this is  
             job[0] = job[0]._render_index
@@ -509,11 +509,11 @@ class RenderNode(object):
             jobcount += 1
             if jobcount >= batch_size:
                 jobcount = 0
-                yield pool.apply_async(func=render_uppertile_batch, args= [batch])
+                yield pool.apply_async(func=render_compositetile_batch, args= [batch])
                 batch = []
                 
         if jobcount > 0:
-            yield pool.apply_async(func=render_uppertile_batch, args= [batch])
+            yield pool.apply_async(func=render_compositetile_batch, args= [batch])
             
 
 ########################################################################################
@@ -542,7 +542,7 @@ def render_worldtile_batch(batch):
     return count
 
 @catch_keyboardinterrupt
-def render_uppertile_batch(batch):
+def render_compositetile_batch(batch):
     global child_rendernode
     rendernode = child_rendernode
     count = 0   
@@ -551,7 +551,7 @@ def render_uppertile_batch(batch):
         count += 1        
         quadtree = rendernode.quadtrees[job[0]]               
         dest = quadtree.full_tiledir+os.sep+job[1]
-        quadtree.render_uppertile(dest=dest,name=job[2])
+        quadtree.render_compositetile(dest=dest,name=job[2])
     return count
 
 @catch_keyboardinterrupt