diff --git a/overviewer_core/tileset.py b/overviewer_core/tileset.py
index 829886d..01b0372 100644
--- a/overviewer_core/tileset.py
+++ b/overviewer_core/tileset.py
@@ -92,6 +92,8 @@ do_work(workobj)
 """
 
 
+TILESET_VERSION = 2  # Update this whenever there is a breaking change with tile renders
+
 # small but useful
 def iterate_base4(d):
     """Iterates over a base 4 number with d digits"""
@@ -309,6 +311,7 @@ class TileSet(object):
 
         self.last_rendertime = config.get('last_rendertime', 0)
         self.forcerendertime = config.get('forcerendertime', 0)
+        self.lastrenderversion = config.get('lastrenderversion', 0)
 
         if "renderchecks" not in self.options:
             # renderchecks was not given, this indicates it was not specified
@@ -318,20 +321,25 @@ class TileSet(object):
                 # No persistent config?
                 if os.path.exists(self.outputdir):
                     # Somehow there's no config but the output dir DOES exist.
-                    # That's strange!
+                    # That's strange! Run forcerender in case of breaking OV version change
                     logging.warning(
                         "For render '%s' I couldn't find any persistent config, "
                         "but I did find my tile directory already exists. This "
                         "shouldn't normally happen, something may be up, but I "
                         "think I can continue...", self.options['name'])
-                    logging.info("Switching to --check-tiles mode")
-                    self.options['renderchecks'] = 1
+                    logging.info("Switching to --forcerender mode")
+                    self.options['renderchecks'] = 2
                 else:
                     # This is the typical code path for an initial render, make
                     # this a "forcerender"
                     self.options['renderchecks'] = 2
                     logging.debug("This is the first time rendering %s. Doing "
                                   "a full-render", self.options['name'])
+            elif self.lastrenderversion != TILESET_VERSION:
+                # Force render in case there is a version change that is breaking
+                logging.warning("Re-rendering world due to version change."
+                                "This will avoid any bad rendering between incompatible versions")
+                self.options['renderchecks'] = 2
             elif not os.path.exists(self.outputdir):
                 # Somehow the outputdir got erased but the metadata file is
                 # still there. That's strange!
@@ -377,6 +385,11 @@ class TileSet(object):
                 self.options['renderchecks'] = 2
             os.mkdir(self.outputdir)
 
+        if self.lastrenderversion != TILESET_VERSION and self.options['renderchecks'] not in [2, 3]:
+            logging.warning("Normally renders from different versions should be"
+                            "overridden or ignored to prevent incompatibilities,"
+                            "but we will honor your decision.")
+
         # must wait until outputdir exists
         self.fs_caps = get_fs_caps(self.outputdir)
 
@@ -591,7 +604,8 @@ class TileSet(object):
             poititle=self.options.get("poititle"),
             showlocationmarker=self.options.get("showlocationmarker"),
             center=(self.options.get("center") or self.options.get("spawn")
-                    or [0, 64, 0])
+                    or [0, 64, 0]),
+            lastrenderversion=TILESET_VERSION
         )
         d['maxZoom'] = self.options.get('maxzoom', self.treedepth)
         if d['maxZoom'] < 0: