diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index ed313d9..8941f89 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -781,44 +781,6 @@
     return result
 
 
-def ZipWrite(zip_file, filename, arcname=None, perms=0o644,
-             compress_type=None):
-  import datetime
-
-  # http://b/18015246
-  # Python 2.7's zipfile implementation wrongly thinks that zip64 is required
-  # for files larger than 2GiB. We can work around this by adjusting their
-  # limit. Note that `zipfile.writestr()` will not work for strings larger than
-  # 2GiB. The Python interpreter sometimes rejects strings that large (though
-  # it isn't clear to me exactly what circumstances cause this).
-  # `zipfile.write()` must be used directly to work around this.
-  #
-  # This mess can be avoided if we port to python3.
-  saved_zip64_limit = zipfile.ZIP64_LIMIT
-  zipfile.ZIP64_LIMIT = (1 << 32) - 1
-
-  compress_type = compress_type or zip_file.compression
-  arcname = arcname or filename
-
-  saved_stat = os.stat(filename)
-
-  try:
-    # `zipfile.write()` doesn't allow us to pass ZipInfo, so just modify the
-    # file to be zipped and reset it when we're done.
-    os.chmod(filename, perms)
-
-    # Use a fixed timestamp so the output is repeatable.
-    epoch = datetime.datetime.fromtimestamp(0)
-    timestamp = (datetime.datetime(2009, 1, 1) - epoch).total_seconds()
-    os.utime(filename, (timestamp, timestamp))
-
-    zip_file.write(filename, arcname=arcname, compress_type=compress_type)
-  finally:
-    os.chmod(filename, saved_stat.st_mode)
-    os.utime(filename, (saved_stat.st_atime, saved_stat.st_mtime))
-    zipfile.ZIP64_LIMIT = saved_zip64_limit
-
-
 def ZipWriteStr(zip, filename, data, perms=0644, compression=None):
   # use a fixed timestamp so the output is repeatable.
   zinfo = zipfile.ZipInfo(filename=filename,
@@ -1112,21 +1074,19 @@
                           self.tgt.TotalSha1(), self.partition))
 
   def _WriteUpdate(self, script, output_zip):
-    ZipWrite(output_zip,
-             '{}.transfer.list'.format(self.path),
-             '{}.transfer.list'.format(self.partition))
-    ZipWrite(output_zip,
-             '{}.new.dat'.format(self.path),
-             '{}.new.dat'.format(self.partition))
-    ZipWrite(output_zip,
-             '{}.patch.dat'.format(self.path),
-             '{}.patch.dat'.format(self.partition),
-             compress_type=zipfile.ZIP_STORED)
+    partition = self.partition
+    with open(self.path + ".transfer.list", "rb") as f:
+      ZipWriteStr(output_zip, partition + ".transfer.list", f.read())
+    with open(self.path + ".new.dat", "rb") as f:
+      ZipWriteStr(output_zip, partition + ".new.dat", f.read())
+    with open(self.path + ".patch.dat", "rb") as f:
+      ZipWriteStr(output_zip, partition + ".patch.dat", f.read(),
+                         compression=zipfile.ZIP_STORED)
 
-    call = ('block_image_update("{device}", '
-            'package_extract_file("{partition}.transfer.list"), '
-            '"{partition}.new.dat", "{partition}.patch.dat");\n'.format(
-                device=self.device, partition=self.partition))
+    call = (('block_image_update("%s", '
+             'package_extract_file("%s.transfer.list"), '
+             '"%s.new.dat", "%s.patch.dat");\n') %
+            (self.device, partition, partition, partition))
     script.AppendExtra(script._WordWrap(call))
 
   def _CheckFirstBlock(self, script):