diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index bae0b20..c4240c4 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -128,6 +128,9 @@
     'odm_dlkm',
 ]
 
+# See sysprop.mk. If file is moved, add new search paths here; don't remove
+# existing search paths.
+RAMDISK_BUILD_PROP_REL_PATHS = ['system/etc/ramdisk/build.prop']
 
 class ErrorCode(object):
   """Define error_codes for failures that happen during the actual
@@ -3569,3 +3572,55 @@
         comment('Move partition %s from default to %s' %
                 (p, u.tgt_group))
         append('move %s %s' % (p, u.tgt_group))
+
+
+def GetBootImageTimestamp(boot_img):
+  """
+  Get timestamp from ramdisk within the boot image
+
+  Args:
+    boot_img: the boot image file. Ramdisk must be compressed with lz4 format.
+
+  Return:
+    An integer that corresponds to the timestamp of the boot image, or None
+    if file has unknown format. Raise exception if an unexpected error has
+    occurred.
+  """
+
+  tmp_dir = MakeTempDir('boot_', suffix='.img')
+  try:
+    RunAndCheckOutput(['unpack_bootimg', '--boot_img', boot_img, '--out', tmp_dir])
+    ramdisk = os.path.join(tmp_dir, 'ramdisk')
+    if not os.path.isfile(ramdisk):
+      logger.warning('Unable to get boot image timestamp: no ramdisk in boot')
+      return None
+    uncompressed_ramdisk = os.path.join(tmp_dir, 'uncompressed_ramdisk')
+    RunAndCheckOutput(['lz4', '-d', ramdisk, uncompressed_ramdisk])
+
+    abs_uncompressed_ramdisk = os.path.abspath(uncompressed_ramdisk)
+    extracted_ramdisk = MakeTempDir('extracted_ramdisk')
+    # Use "toybox cpio" instead of "cpio" because the latter invokes cpio from
+    # the host environment.
+    RunAndCheckOutput(['toybox', 'cpio', '-F', abs_uncompressed_ramdisk, '-i'],
+               cwd=extracted_ramdisk)
+
+    prop_file = None
+    for search_path in RAMDISK_BUILD_PROP_REL_PATHS:
+      prop_file = os.path.join(extracted_ramdisk, search_path)
+      if os.path.isfile(prop_file):
+        break
+      logger.warning('Unable to get boot image timestamp: no %s in ramdisk', search_path)
+
+    if not prop_file:
+      return None
+
+    props = PartitionBuildProps.FromBuildPropFile('boot', prop_file)
+    timestamp = props.GetProp('ro.bootimage.build.date.utc')
+    if timestamp:
+      return int(timestamp)
+    logger.warning('Unable to get boot image timestamp: ro.bootimage.build.date.utc is undefined')
+    return None
+
+  except ExternalError as e:
+    logger.warning('Unable to get boot image timestamp: %s', e)
+    return None
diff --git a/tools/releasetools/ota_utils.py b/tools/releasetools/ota_utils.py
index cb0f6e6..be6a134 100644
--- a/tools/releasetools/ota_utils.py
+++ b/tools/releasetools/ota_utils.py
@@ -21,8 +21,7 @@
 import ota_metadata_pb2
 from common import (ZipDelete, ZipClose, OPTIONS, MakeTempFile,
                     ZipWriteStr, BuildInfo, LoadDictionaryFromFile,
-                    SignFile, PARTITIONS_WITH_CARE_MAP, PartitionBuildProps,
-                    MakeTempDir, RunAndCheckOutput, ExternalError)
+                    SignFile, PARTITIONS_WITH_CARE_MAP, PartitionBuildProps)
 
 logger = logging.getLogger(__name__)
 
@@ -41,10 +40,6 @@
 METADATA_PROTO_NAME = 'META-INF/com/android/metadata.pb'
 UNZIP_PATTERN = ['IMAGES/*', 'META/*', 'OTA/*', 'RADIO/*']
 
-# See sysprop.mk. If file is moved, add new search paths here; don't remove
-# existing search paths.
-RAMDISK_BUILD_PROP_REL_PATHS = ['system/etc/ramdisk/build.prop']
-
 def FinalizeMetadata(metadata, input_file, output_file, needed_property_files):
   """Finalizes the metadata and signs an A/B OTA package.
 
@@ -567,55 +562,3 @@
 
   SignFile(temp_zip_name, output_zip_name, OPTIONS.package_key, pw,
            whole_file=True)
-
-
-def GetBootImageTimestamp(boot_img):
-  """
-  Get timestamp from ramdisk within the boot image
-
-  Args:
-    boot_img: the boot image file. Ramdisk must be compressed with lz4 format.
-
-  Return:
-    An integer that corresponds to the timestamp of the boot image, or None
-    if file has unknown format. Raise exception if an unexpected error has
-    occurred.
-  """
-
-  tmp_dir = MakeTempDir('boot_', suffix='.img')
-  try:
-    RunAndCheckOutput(['unpack_bootimg', '--boot_img', boot_img, '--out', tmp_dir])
-    ramdisk = os.path.join(tmp_dir, 'ramdisk')
-    if not os.path.isfile(ramdisk):
-      logger.warning('Unable to get boot image timestamp: no ramdisk in boot')
-      return None
-    uncompressed_ramdisk = os.path.join(tmp_dir, 'uncompressed_ramdisk')
-    RunAndCheckOutput(['lz4', '-d', ramdisk, uncompressed_ramdisk])
-
-    abs_uncompressed_ramdisk = os.path.abspath(uncompressed_ramdisk)
-    extracted_ramdisk = MakeTempDir('extracted_ramdisk')
-    # Use "toybox cpio" instead of "cpio" because the latter invokes cpio from
-    # the host environment.
-    RunAndCheckOutput(['toybox', 'cpio', '-F', abs_uncompressed_ramdisk, '-i'],
-               cwd=extracted_ramdisk)
-
-    prop_file = None
-    for search_path in RAMDISK_BUILD_PROP_REL_PATHS:
-      prop_file = os.path.join(extracted_ramdisk, search_path)
-      if os.path.isfile(prop_file):
-        break
-      logger.warning('Unable to get boot image timestamp: no %s in ramdisk', search_path)
-
-    if not prop_file:
-      return None
-
-    props = PartitionBuildProps.FromBuildPropFile('boot', prop_file)
-    timestamp = props.GetProp('ro.bootimage.build.date.utc')
-    if timestamp:
-      return int(timestamp)
-    logger.warning('Unable to get boot image timestamp: ro.bootimage.build.date.utc is undefined')
-    return None
-
-  except ExternalError as e:
-    logger.warning('Unable to get boot image timestamp: %s', e)
-    return None