diff --git a/bootstrap.py b/bootstrap.py
index ed57894..a629566 100644
--- a/bootstrap.py
+++ b/bootstrap.py
@@ -35,7 +35,7 @@
 Simply run this script in a directory containing a buildout.cfg, using the
 Python that you want bin/buildout to use.
 
-Note that by using --find-links to point to local resources, you can keep 
+Note that by using --find-links to point to local resources, you can keep
 this script from going over the network.
 '''
 
@@ -59,6 +59,8 @@
 parser.add_option("--allow-site-packages",
                   action="store_true", default=False,
                   help=("Let bootstrap.py use existing site packages"))
+parser.add_option("--setuptools-version",
+                  help="use a specific setuptools version")
 
 
 options, args = parser.parse_args()
@@ -79,16 +81,20 @@
 
 if not options.allow_site_packages:
     # ez_setup imports site, which adds site packages
-    # this will remove them from the path to ensure that incompatible versions 
+    # this will remove them from the path to ensure that incompatible versions
     # of setuptools are not in the path
     import site
-    # inside a virtualenv, there is no 'getsitepackages'. 
+    # inside a virtualenv, there is no 'getsitepackages'.
     # We can't remove these reliably
     if hasattr(site, 'getsitepackages'):
         for sitepackage_path in site.getsitepackages():
             sys.path[:] = [x for x in sys.path if sitepackage_path not in x]
 
 setup_args = dict(to_dir=tmpeggs, download_delay=0)
+
+if options.setuptools_version is not None:
+    setup_args['version'] = options.setuptools_version
+
 ez['use_setuptools'](**setup_args)
 import setuptools
 import pkg_resources
@@ -128,10 +134,15 @@
     _final_parts = '*final-', '*final'
 
     def _final_version(parsed_version):
-        for part in parsed_version:
-            if (part[:1] == '*') and (part not in _final_parts):
-                return False
-        return True
+        try:
+            return not parsed_version.is_prerelease
+        except AttributeError:
+            # Older setuptools
+            for part in parsed_version:
+                if (part[:1] == '*') and (part not in _final_parts):
+                    return False
+            return True
+
     index = setuptools.package_index.PackageIndex(
         search_path=[setuptools_path])
     if find_links: