diff --git a/ironic/common/utils.py b/ironic/common/utils.py
index 30244e4e55..ab2788a51d 100644
--- a/ironic/common/utils.py
+++ b/ironic/common/utils.py
@@ -295,7 +295,7 @@ def file_has_content(path, content, hash_algo='md5'):
     :returns: True if the hash of reference content is the same as
         the hash of file's content, False otherwise
     """
-    with open(path) as existing:
+    with open(path, 'rb') as existing:
         file_hash_hex = hash_file(existing, hash_algo=hash_algo)
     ref_hash = _get_hash_object(hash_algo)
     ref_hash.update(content)
diff --git a/ironic/tests/unit/common/test_utils.py b/ironic/tests/unit/common/test_utils.py
index 48527e7dee..cfb5e91c3f 100644
--- a/ironic/tests/unit/common/test_utils.py
+++ b/ironic/tests/unit/common/test_utils.py
@@ -250,15 +250,17 @@ class GenericUtilsTestCase(base.TestCase):
         data = b'Mary had a little lamb, its fleece as white as snow'
         ref = data
         with mock.patch('ironic.common.utils.open',
-                        mock.mock_open(read_data=data)):
+                        mock.mock_open(read_data=data)) as mopen:
             self.assertTrue(utils.file_has_content('foo', ref))
+            mopen.assert_called_once_with('foo', 'rb')
 
     def test_file_has_content_differ(self):
         data = b'Mary had a little lamb, its fleece as white as snow'
         ref = data + b'!'
         with mock.patch('ironic.common.utils.open',
-                        mock.mock_open(read_data=data)):
+                        mock.mock_open(read_data=data)) as mopen:
             self.assertFalse(utils.file_has_content('foo', ref))
+            mopen.assert_called_once_with('foo', 'rb')
 
     def test_is_valid_datapath_id(self):
         self.assertTrue(utils.is_valid_datapath_id("525400cf2d319fdf"))