diff --git a/git_config.py b/git_config.py
index a667b3f8..aa07d1b7 100644
--- a/git_config.py
+++ b/git_config.py
@@ -697,7 +697,7 @@ class Branch(object):
       self._Set('merge', self.merge)
 
     else:
-      fd = open(self._config.file, 'ab')
+      fd = open(self._config.file, 'a')
       try:
         fd.write('[branch "%s"]\n' % self.name)
         if self.remote:
diff --git a/project.py b/project.py
index 460bf315..95403ccb 100644
--- a/project.py
+++ b/project.py
@@ -46,7 +46,7 @@ if not is_python3():
 def _lwrite(path, content):
   lock = '%s.lock' % path
 
-  fd = open(lock, 'wb')
+  fd = open(lock, 'w')
   try:
     fd.write(content)
   finally: