diff --git a/tools/releasetools/add_img_to_target_files.py b/tools/releasetools/add_img_to_target_files.py
index b8c812d..f3b58f8 100644
--- a/tools/releasetools/add_img_to_target_files.py
+++ b/tools/releasetools/add_img_to_target_files.py
@@ -1030,8 +1030,5 @@
   try:
     common.CloseInheritedPipes()
     main(sys.argv[1:])
-  except common.ExternalError:
-    logger.exception("\n   ERROR:\n")
-    sys.exit(1)
   finally:
     common.Cleanup()
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index bcc10bd..1f3022b 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -241,7 +241,7 @@
 import common
 import ota_utils
 from ota_utils import (UNZIP_PATTERN, FinalizeMetadata, GetPackageMetadata,
-                       PropertyFiles, SECURITY_PATCH_LEVEL_PROP_NAME)
+                       PropertyFiles, SECURITY_PATCH_LEVEL_PROP_NAME, GetZipEntryOffset)
 import target_files_diff
 from check_target_files_vintf import CheckVintfIfTrebleEnabled
 from non_ab_ota import GenerateNonAbOtaPackage
@@ -603,20 +603,20 @@
     payload, till the end of 'medatada_signature_message'.
     """
     payload_info = input_zip.getinfo('payload.bin')
-    payload_offset = payload_info.header_offset
-    payload_offset += zipfile.sizeFileHeader
-    payload_offset += len(payload_info.extra) + len(payload_info.filename)
-    payload_size = payload_info.file_size
+    (payload_offset, payload_size) = GetZipEntryOffset(input_zip, payload_info)
 
-    with input_zip.open('payload.bin') as payload_fp:
-      header_bin = payload_fp.read(24)
+    # Read the underlying raw zipfile at specified offset
+    payload_fp = input_zip.fp
+    payload_fp.seek(payload_offset)
+    header_bin = payload_fp.read(24)
 
     # network byte order (big-endian)
     header = struct.unpack("!IQQL", header_bin)
 
     # 'CrAU'
     magic = header[0]
-    assert magic == 0x43724155, "Invalid magic: {:x}".format(magic)
+    assert magic == 0x43724155, "Invalid magic: {:x}, computed offset {}" \
+        .format(magic, payload_offset)
 
     manifest_size = header[2]
     metadata_signature_size = header[3]
diff --git a/tools/releasetools/ota_utils.py b/tools/releasetools/ota_utils.py
index 28c246b..5737009 100644
--- a/tools/releasetools/ota_utils.py
+++ b/tools/releasetools/ota_utils.py
@@ -16,6 +16,7 @@
 import itertools
 import logging
 import os
+import struct
 import zipfile
 
 import ota_metadata_pb2
@@ -399,6 +400,35 @@
   return device_names, fingerprints
 
 
+def GetZipEntryOffset(zfp, entry_info):
+  """Get offset to a beginning of a particular zip entry
+  Args:
+    fp: zipfile.ZipFile
+    entry_info: zipfile.ZipInfo
+
+  Returns:
+    (offset, size) tuple
+  """
+  # Don't use len(entry_info.extra). Because that returns size of extra
+  # fields in central directory. We need to look at local file directory,
+  # as these two might have different sizes.
+
+  # We cannot work with zipfile.ZipFile instances, we need a |fp| for the underlying file.
+  zfp = zfp.fp
+  zfp.seek(entry_info.header_offset)
+  data = zfp.read(zipfile.sizeFileHeader)
+  fheader = struct.unpack(zipfile.structFileHeader, data)
+  # Last two fields of local file header are filename length and
+  # extra length
+  filename_len = fheader[-2]
+  extra_len = fheader[-1]
+  offset = entry_info.header_offset
+  offset += zipfile.sizeFileHeader
+  offset += filename_len + extra_len
+  size = entry_info.file_size
+  return (offset, size)
+
+
 class PropertyFiles(object):
   """A class that computes the property-files string for an OTA package.
 
@@ -517,10 +547,7 @@
     def ComputeEntryOffsetSize(name):
       """Computes the zip entry offset and size."""
       info = zip_file.getinfo(name)
-      offset = info.header_offset
-      offset += zipfile.sizeFileHeader
-      offset += len(info.extra) + len(info.filename)
-      size = info.file_size
+      (offset, size) = GetZipEntryOffset(zip_file, info)
       return '%s:%d:%d' % (os.path.basename(name), offset, size)
 
     tokens = []
diff --git a/tools/releasetools/test_ota_utils.py b/tools/releasetools/test_ota_utils.py
new file mode 100644
index 0000000..9a82e6f
--- /dev/null
+++ b/tools/releasetools/test_ota_utils.py
@@ -0,0 +1,56 @@
+# Copyright (C) 2021 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import unittest
+import io
+import ota_utils
+import zipfile
+
+
+class TestZipEntryOffset(unittest.TestCase):
+  def test_extra_length_differ(self):
+      # This is a magic zip file such that:
+      # 1. It has 1 entry, `file.txt'`
+      # 2. The central directory entry for the entry contains an extra field of#
+      # length 24, while the local file header for the entry contains an extra#
+      # field of length 28.
+      # It is key that the entry contains extra field of different length.
+      # The sole purpose of this test case is make sure our offset computing
+      # logic works in this scenario.
+
+      # This is created by:
+      # touch file.txt
+      # zip -0 test.zip file.txt
+      # Above command may or may not work on all platforms.
+      # Some zip implementation will keep the extra field size consistent.
+      # Some don't
+    magic_zip = b'PK\x03\x04\n\x00\x00\x00\x00\x00nY\xfcR\x00\x00\x00\x00\x00\x00\x00' +\
+        b'\x00\x00\x00\x00\x00\x08\x00\x1c\x00file.txtUT\t\x00\x03' +\
+        b'\xa0s\x01a\xa0s\x01aux\x0b\x00\x01\x04\x88\xc4\t\x00\x04S_\x01\x00' +\
+        b'PK\x01\x02\x1e\x03\n\x00\x00\x00\x00\x00nY\xfcR\x00\x00\x00\x00' +\
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x18\x00\x00\x00\x00\x00' +\
+        b'\x00\x00\x00\x00\x80\x81\x00\x00\x00\x00file.txt' +\
+        b'UT\x05\x00\x03\xa0s\x01aux\x0b\x00\x01\x04\x88\xc4\t\x00\x04' +\
+        b'S_\x01\x00PK\x05\x06\x00\x00\x00\x00\x01\x00\x01\x00N\x00\x00' +\
+        b'\x00B\x00\x00\x00\x00\x00'
+    # Just making sure we concatenated the bytes correctly
+    self.assertEqual(len(magic_zip), 166)
+    fp = io.BytesIO(magic_zip)
+    with zipfile.ZipFile(fp, 'r') as zfp:
+      self.assertGreater(len(zfp.infolist()), 0)
+      zinfo = zfp.getinfo("file.txt")
+      (offset, size) = ota_utils.GetZipEntryOffset(zfp, zinfo)
+      self.assertEqual(size, zinfo.file_size)
+      self.assertEqual(offset, zipfile.sizeFileHeader+len(zinfo.filename) + 28)