diff --git a/overviewer.py b/overviewer.py
index 5f3400c..e217949 100755
--- a/overviewer.py
+++ b/overviewer.py
@@ -94,6 +94,7 @@ def main():
     parser.add_option("-z", "--zoom", dest="zoom", help="Sets the zoom level manually instead of calculating it. This can be useful if you have outlier chunks that make your world too big. This value will make the highest zoom level contain (2**ZOOM)^2 tiles", action="store", type="int", configFileOnly=True)
     parser.add_option("-d", "--delete", dest="delete", help="Clear all caches. Next time you render your world, it will have to start completely over again. This is probably not a good idea for large worlds. Use this if you change texture packs and want to re-render everything.", action="store_true", commandLineOnly=True)
     parser.add_option("--regionlist", dest="regionlist", help="A file containing, on each line, a path to a regionlist to update. Instead of scanning the world directory for regions, it will just use this list. Normal caching rules still apply.")
+    parser.add_option("--forcerender", dest="forcerender", help="Force re-rendering the entire map (or the given regionlist). Useful for re-rendering without deleting the entire map with --delete.", action="store_true")
     parser.add_option("--rendermodes", dest="rendermode", help="Specifies the render types, separated by commas. Use --list-rendermodes to list them all.", type="choice", choices=avail_rendermodes, required=True, default=avail_rendermodes[0], listify=True)
     parser.add_option("--list-rendermodes", dest="list_rendermodes", action="store_true", help="List available render modes and exit.", commandLineOnly=True)
     parser.add_option("--imgformat", dest="imgformat", help="The image output format to use. Currently supported: png(default), jpg.", configFileOnly=True )
@@ -231,7 +232,7 @@ def main():
     # create the quadtrees
     # TODO chunklist
     q = []
-    qtree_args = {'depth' : options.zoom, 'imgformat' : imgformat, 'imgquality' : options.imgquality, 'optimizeimg' : optimizeimg, 'bgcolor' : bgcolor}
+    qtree_args = {'depth' : options.zoom, 'imgformat' : imgformat, 'imgquality' : options.imgquality, 'optimizeimg' : optimizeimg, 'bgcolor' : bgcolor, 'forcerender' : options.forcerender}
     for rendermode in options.rendermode:
         if rendermode == 'normal':
             qtree = quadtree.QuadtreeGen(w, destdir, rendermode=rendermode, tiledir='tiles', **qtree_args)
diff --git a/quadtree.py b/quadtree.py
index 5d240db..f1c4b1d 100644
--- a/quadtree.py
+++ b/quadtree.py
@@ -49,7 +49,7 @@ def iterate_base4(d):
     return itertools.product(xrange(4), repeat=d)
    
 class QuadtreeGen(object):
-    def __init__(self, worldobj, destdir, bgcolor, depth=None, tiledir=None, imgformat=None, imgquality=95, optimizeimg=None, rendermode="normal"):
+    def __init__(self, worldobj, destdir, bgcolor, depth=None, tiledir=None, forcerender=False, imgformat=None, imgquality=95, optimizeimg=None, rendermode="normal"):
         """Generates a quadtree from the world given into the
         given dest directory
 
@@ -60,6 +60,7 @@ class QuadtreeGen(object):
 
         """
         assert(imgformat)
+        self.forcerender = forcerender
         self.imgformat = imgformat
         self.imgquality = imgquality
         self.optimizeimg = optimizeimg
@@ -425,10 +426,17 @@ class QuadtreeGen(object):
             needs_rerender = False
             get_region_mtime = world.get_region_mtime
             for col, row, chunkx, chunky, regionfile in chunks:
-                # check region file mtime first. 
-                region,regionMtime = get_region_mtime(regionfile)  
+                # don't even check if it's not in the regionlist
                 if self.world.regionlist and region._filename not in self.world.regionlist:
                     continue
+                
+                # bail early if forcerender is set
+                if self.forcerender:
+                    needs_rerender = True
+                    break
+                
+                # check region file mtime first. 
+                region,regionMtime = get_region_mtime(regionfile)
                 if regionMtime <= tile_mtime:
                     continue