diff --git a/CHANGELOG.md b/CHANGELOG.md
index cab1cbc..9179b65 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Fixed
+
+- Ignore null characters in the input CSV file
+  https://github.com/OpenDataServices/flatten-tool/pull/435
+
 ## [0.24.0] - 2023-11-15
 
 ### Changed
diff --git a/flattentool/input.py b/flattentool/input.py
index cc9137a..80d007d 100644
--- a/flattentool/input.py
+++ b/flattentool/input.py
@@ -44,6 +44,21 @@ def __init__(self, cell_value, cell_location):
         self.sub_cells = []
 
 
+# Avoid _csv.Error "line contains NUL" in Python < 3.11.
+class NullCharacterFilter:
+    def __init__(self, file):
+        self.file = file
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        """
+        Remove null characters read from the file.
+        """
+        return next(self.file).replace("\0", "")
+
+
 def convert_type(type_string, value, timezone=pytz.timezone("UTC"), convert_flags={}):
     if value == "" or value is None:
         return None
@@ -615,7 +630,7 @@ def get_sheet_headings(self, sheet_name):
         with open(
             os.path.join(self.input_name, sheet_name + ".csv"), encoding=self.encoding
         ) as main_sheet_file:
-            r = csvreader(main_sheet_file)
+            r = csvreader(NullCharacterFilter(main_sheet_file))
             for num, row in enumerate(r):
                 if num == (skip_rows + configuration_line):
                     return row
diff --git a/flattentool/tests/test_input.py b/flattentool/tests/test_input.py
index ce8a05e..5ea04b6 100644
--- a/flattentool/tests/test_input.py
+++ b/flattentool/tests/test_input.py
@@ -5,7 +5,13 @@
 """
 from __future__ import unicode_literals
 
-from flattentool.input import path_search
+import csv
+import io
+import sys
+
+import pytest
+
+from flattentool.input import NullCharacterFilter, path_search
 
 
 def test_path_search():
@@ -42,3 +48,15 @@ def test_path_search():
         )
         is goal_dict
     )
+
+
+def test_null_character_filter():
+    # https://bugs.python.org/issue27580
+    if sys.version_info < (3, 11):
+        with pytest.raises(Exception):
+            next(csv.reader(io.StringIO("\0")))
+
+    try:
+        next(csv.reader(NullCharacterFilter(io.StringIO("\0"))))
+    except Exception as e:
+        pytest.fail(str(e))