diff --git a/git_config.py b/git_config.py
index 32879ec..380bdd2 100644
--- a/git_config.py
+++ b/git_config.py
@@ -15,8 +15,8 @@
 
 from __future__ import print_function
 
+import json
 import os
-import pickle
 import re
 import subprocess
 import sys
@@ -80,7 +80,7 @@
     return cls(configfile = os.path.join(gitdir, 'config'),
                defaults = defaults)
 
-  def __init__(self, configfile, defaults=None, pickleFile=None):
+  def __init__(self, configfile, defaults=None, jsonFile=None):
     self.file = configfile
     self.defaults = defaults
     self._cache_dict = None
@@ -88,12 +88,11 @@
     self._remotes = {}
     self._branches = {}
 
-    if pickleFile is None:
-      self._pickle = os.path.join(
+    self._json = jsonFile
+    if self._json is None:
+      self._json = os.path.join(
         os.path.dirname(self.file),
-        '.repopickle_' + os.path.basename(self.file))
-    else:
-      self._pickle = pickleFile
+        '.repo_' + os.path.basename(self.file) + '.json')
 
   def Has(self, name, include_defaults = True):
     """Return true if this configuration file has the key.
@@ -248,50 +247,41 @@
     return self._cache_dict
 
   def _Read(self):
-    d = self._ReadPickle()
+    d = self._ReadJson()
     if d is None:
       d = self._ReadGit()
-      self._SavePickle(d)
+      self._SaveJson(d)
     return d
 
-  def _ReadPickle(self):
+  def _ReadJson(self):
     try:
-      if os.path.getmtime(self._pickle) \
+      if os.path.getmtime(self._json) \
       <= os.path.getmtime(self.file):
-        os.remove(self._pickle)
+        os.remove(self._json)
         return None
     except OSError:
       return None
     try:
-      Trace(': unpickle %s', self.file)
-      fd = open(self._pickle, 'rb')
+      Trace(': parsing %s', self.file)
+      fd = open(self._json)
       try:
-        return pickle.load(fd)
+        return json.load(fd)
       finally:
         fd.close()
-    except EOFError:
-      os.remove(self._pickle)
-      return None
-    except IOError:
-      os.remove(self._pickle)
-      return None
-    except pickle.PickleError:
-      os.remove(self._pickle)
+    except (IOError, ValueError):
+      os.remove(self._json)
       return None
 
-  def _SavePickle(self, cache):
+  def _SaveJson(self, cache):
     try:
-      fd = open(self._pickle, 'wb')
+      fd = open(self._json, 'w')
       try:
-        pickle.dump(cache, fd, pickle.HIGHEST_PROTOCOL)
+        json.dump(cache, fd, indent=2)
       finally:
         fd.close()
-    except IOError:
-      if os.path.exists(self._pickle):
-        os.remove(self._pickle)
-    except pickle.PickleError:
-      if os.path.exists(self._pickle):
-        os.remove(self._pickle)
+    except (IOError, TypeError):
+      if os.path.exists(self.json):
+        os.remove(self._json)
 
   def _ReadGit(self):
     """
diff --git a/manifest_xml.py b/manifest_xml.py
index 6557477..a79f714 100644
--- a/manifest_xml.py
+++ b/manifest_xml.py
@@ -872,10 +872,8 @@
     fromProjects = self.paths
     toProjects = manifest.paths
 
-    fromKeys = fromProjects.keys()
-    fromKeys.sort()
-    toKeys = toProjects.keys()
-    toKeys.sort()
+    fromKeys = sorted(fromProjects.keys())
+    toKeys = sorted(toProjects.keys())
 
     diff = {'added': [], 'removed': [], 'changed': [], 'unreachable': []}
 
diff --git a/project.py b/project.py
index 127176e..55c188d 100644
--- a/project.py
+++ b/project.py
@@ -438,7 +438,8 @@
       # and  convert to a HookError w/ just the failing traceback.
       context = {}
       try:
-        execfile(self._script_fullpath, context)
+        exec(compile(open(self._script_fullpath).read(),
+                     self._script_fullpath, 'exec'), context)
       except Exception:
         raise HookError('%s\nFailed to import %s hook; see traceback above.' % (
                         traceback.format_exc(), self._hook_type))
@@ -2321,8 +2322,8 @@
           out = iter(out[:-1].split('\0'))  # pylint: disable=W1401
           while out:
             try:
-              info = out.next()
-              path = out.next()
+              info = next(out)
+              path = next(out)
             except StopIteration:
               break
 
@@ -2348,7 +2349,7 @@
             info = _Info(path, *info)
             if info.status in ('R', 'C'):
               info.src_path = info.path
-              info.path = out.next()
+              info.path = next(out)
             r[info.path] = info
         return r
       finally:
diff --git a/repo b/repo
index b8c414b..3fd0166 100755
--- a/repo
+++ b/repo
@@ -139,10 +139,6 @@
 
 # Python version check
 ver = sys.version_info
-if ver[0] == 3:
-  _print('warning: Python 3 support is currently experimental. YMMV.\n'
-         'Please use Python 2.6 - 2.7 instead.',
-         file=sys.stderr)
 if (ver[0], ver[1]) < MIN_PYTHON_VERSION:
   _print('error: Python version %s unsupported.\n'
          'Please use Python 2.6 - 2.7 instead.'
@@ -768,4 +764,8 @@
 
 
 if __name__ == '__main__':
+  if ver[0] == 3:
+    _print('warning: Python 3 support is currently experimental. YMMV.\n'
+           'Please use Python 2.6 - 2.7 instead.',
+           file=sys.stderr)
   main(sys.argv[1:])
diff --git a/subcmds/status.py b/subcmds/status.py
index 41c4429..b42675e 100644
--- a/subcmds/status.py
+++ b/subcmds/status.py
@@ -113,7 +113,7 @@
     try:
       state = project.PrintWorkTreeStatus(output)
       if state == 'CLEAN':
-        clean_counter.next()
+        next(clean_counter)
     finally:
       sem.release()
 
@@ -141,7 +141,7 @@
       for project in all_projects:
         state = project.PrintWorkTreeStatus()
         if state == 'CLEAN':
-          counter.next()
+          next(counter)
     else:
       sem = _threading.Semaphore(opt.jobs)
       threads_and_output = []
@@ -164,7 +164,7 @@
         t.join()
         output.dump(sys.stdout)
         output.close()
-    if len(all_projects) == counter.next():
+    if len(all_projects) == next(counter):
       print('nothing to commit (working directory clean)')
 
     if opt.orphans:
diff --git a/subcmds/sync.py b/subcmds/sync.py
index a0a6896..6f77310 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -14,10 +14,10 @@
 # limitations under the License.
 
 from __future__ import print_function
+import json
 import netrc
 from optparse import SUPPRESS_HELP
 import os
-import pickle
 import re
 import shutil
 import socket
@@ -760,7 +760,7 @@
   _ALPHA = 0.5
 
   def __init__(self, manifest):
-    self._path = os.path.join(manifest.repodir, '.repopickle_fetchtimes')
+    self._path = os.path.join(manifest.repodir, '.repo_fetchtimes.json')
     self._times = None
     self._seen = set()
 
@@ -779,22 +779,17 @@
   def _Load(self):
     if self._times is None:
       try:
-        f = open(self._path, 'rb')
-      except IOError:
-        self._times = {}
-        return self._times
-      try:
+        f = open(self._path)
         try:
-          self._times = pickle.load(f)
-        except IOError:
-          try:
-            os.remove(self._path)
-          except OSError:
-            pass
-          self._times = {}
-      finally:
-        f.close()
-    return self._times
+          self._times = json.load(f)
+        finally:
+          f.close()
+      except (IOError, ValueError):
+        try:
+          os.remove(self._path)
+        except OSError:
+          pass
+        self._times = {}
 
   def Save(self):
     if self._times is None:
@@ -808,13 +803,13 @@
       del self._times[name]
 
     try:
-      f = open(self._path, 'wb')
+      f = open(self._path, 'w')
       try:
-        pickle.dump(self._times, f)
-      except (IOError, OSError, pickle.PickleError):
-        try:
-          os.remove(self._path)
-        except OSError:
-          pass
-    finally:
-      f.close()
+        json.dump(self._times, f, indent=2)
+      finally:
+        f.close()
+    except (IOError, TypeError):
+      try:
+        os.remove(self._path)
+      except OSError:
+        pass
diff --git a/subcmds/upload.py b/subcmds/upload.py
index e2fa261..0ee36df 100644
--- a/subcmds/upload.py
+++ b/subcmds/upload.py
@@ -25,10 +25,12 @@
 from project import RepoHook
 
 from pyversion import is_python3
+# pylint:disable=W0622
 if not is_python3():
-  # pylint:disable=W0622
   input = raw_input
-  # pylint:enable=W0622
+else:
+  unicode = str
+# pylint:enable=W0622
 
 UNUSUAL_COMMIT_THRESHOLD = 5