diff --git a/chalice-master/chalice/deploy/packager.py b/chalice-master/chalice/deploy/packager.py
index 53badce..f9df408 100644
--- a/chalice-master/chalice/deploy/packager.py
+++ b/chalice-master/chalice/deploy/packager.py
@@ -178,7 +178,7 @@ def _hash_project_dir(self, requirements_filename, vendor_dir,
         else:
             contents = cast(bytes, self._osutils.get_file_contents(
                 requirements_filename, binary=True))
-        h = hashlib.md5(contents)
+        h = hashlib.sha256(contents)
         for filename, _ in self._iter_app_filenames(project_dir):
             with self._osutils.open(filename, 'rb') as f:
                 reader = functools.partial(f.read, 1024 * 1024)