diff --git a/git_command.py b/git_command.py
index 4ad908f..4aeacd5 100644
--- a/git_command.py
+++ b/git_command.py
@@ -112,6 +112,9 @@
     sys.exit(1)
   return False
 
+def _setenv(env, name, value):
+  env[name] = value.encode()
+
 class GitCommand(object):
   def __init__(self,
                project,
@@ -137,10 +140,10 @@
         del env[e]
 
     if disable_editor:
-      env['GIT_EDITOR'] = ':'
+      _setenv(env, 'GIT_EDITOR', ':')
     if ssh_proxy:
-      env['REPO_SSH_SOCK'] = ssh_sock()
-      env['GIT_SSH'] = _ssh_proxy()
+      _setenv(env, 'REPO_SSH_SOCK', ssh_sock())
+      _setenv(env, 'GIT_SSH', _ssh_proxy())
 
     if project:
       if not cwd:
@@ -151,7 +154,7 @@
     command = [GIT]
     if bare:
       if gitdir:
-        env[GIT_DIR] = gitdir
+        _setenv(env, GIT_DIR, gitdir)
       cwd = None
     command.extend(cmdv)
 
diff --git a/repo b/repo
index 6f2067e..02858ec 100755
--- a/repo
+++ b/repo
@@ -259,8 +259,8 @@
             gpg_dir, e.strerror)
       sys.exit(1)
 
-  env = dict(os.environ)
-  env['GNUPGHOME'] = gpg_dir
+  env = os.environ.copy()
+  env['GNUPGHOME'] = gpg_dir.encode()
 
   cmd = ['gpg', '--import']
   try:
@@ -378,8 +378,8 @@
         % (branch, cur)
       print >>sys.stderr
 
-  env = dict(os.environ)
-  env['GNUPGHOME'] = gpg_dir
+  env = os.environ.copy()
+  env['GNUPGHOME'] = gpg_dir.encode()
 
   cmd = [GIT, 'tag', '-v', cur]
   proc = subprocess.Popen(cmd,
diff --git a/subcmds/forall.py b/subcmds/forall.py
index b66313d..8209c80 100644
--- a/subcmds/forall.py
+++ b/subcmds/forall.py
@@ -151,11 +151,11 @@
     first = True
 
     for project in self.GetProjects(args):
-      env = dict(os.environ.iteritems())
+      env = os.environ.copy()
       def setenv(name, val):
         if val is None:
           val = ''
-        env[name] = val
+        env[name] = val.encode()
 
       setenv('REPO_PROJECT', project.name)
       setenv('REPO_PATH', project.relpath)
diff --git a/subcmds/sync.py b/subcmds/sync.py
index d6ea442..80bba1a 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -269,7 +269,7 @@
         if branch.startswith(R_HEADS):
           branch = branch[len(R_HEADS):]
 
-        env = dict(os.environ)
+        env = os.environ.copy()
         if (env.has_key('TARGET_PRODUCT') and
             env.has_key('TARGET_BUILD_VARIANT')):
           target = '%s-%s' % (env['TARGET_PRODUCT'],
@@ -413,9 +413,9 @@
       % (project.name, rev)
     return False
 
-  env = dict(os.environ)
-  env['GIT_DIR'] = project.gitdir
-  env['GNUPGHOME'] = gpg_dir
+  env = os.environ.copy()
+  env['GIT_DIR'] = project.gitdir.encode()
+  env['GNUPGHOME'] = gpg_dir.encode()
 
   cmd = [GIT, 'tag', '-v', cur]
   proc = subprocess.Popen(cmd,