diff --git a/project.py b/project.py
index e0419e7a..67d3bb20 100755
--- a/project.py
+++ b/project.py
@@ -2261,8 +2261,8 @@ class Project(object):
 
   def _IsValidBundle(self, path, quiet):
     try:
-      with open(path) as f:
-        if f.read(16) == '# v2 git bundle\n':
+      with open(path, 'rb') as f:
+        if f.read(16) == b'# v2 git bundle\n':
           return True
         else:
           if not quiet: