diff --git a/scripts/code_style.py b/scripts/code_style.py
new file mode 100755
index 0000000..7923db4
--- /dev/null
+++ b/scripts/code_style.py
@@ -0,0 +1,153 @@
+#!/usr/bin/env python3
+"""Check or fix the code style by running Uncrustify.
+"""
+# Copyright The Mbed TLS Contributors
+# SPDX-License-Identifier: Apache-2.0
+#
+# 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 argparse
+import io
+import os
+import subprocess
+import sys
+from typing import List
+
+CONFIG_FILE = "codestyle.cfg"
+UNCRUSTIFY_EXE = "uncrustify"
+UNCRUSTIFY_ARGS = ["-c", CONFIG_FILE]
+STDOUT_UTF8 = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8')
+STDERR_UTF8 = io.TextIOWrapper(sys.stderr.buffer, encoding='utf-8')
+
+def get_src_files() -> List[str]:
+    """
+    Use git ls-files to get a list of the source files
+    """
+    git_ls_files_cmd = ["git", "ls-files", \
+            "*.[hc]", \
+            "tests/suites/*.function", \
+            "scripts/data_files/*.fmt"]
+
+    result = subprocess.run(git_ls_files_cmd, stdout=subprocess.PIPE, \
+            stderr=STDERR_UTF8, check=False)
+
+    if result.returncode != 0:
+        print("Error: git ls-files returned: "+str(result.returncode), \
+                file=STDERR_UTF8)
+        return []
+    else:
+        src_files = str(result.stdout, "utf-8").split()
+        # Don't correct style for files in 3rdparty/
+        src_files = list(filter( \
+                lambda filename: not filename.startswith("3rdparty/"), \
+                src_files))
+        return src_files
+
+def get_uncrustify_version() -> str:
+    """
+    Get the version string from Uncrustify
+    """
+    version_args = ["--version"]
+    result = subprocess.run([UNCRUSTIFY_EXE] + version_args, \
+            stdout=subprocess.PIPE, stderr=subprocess.PIPE, check=False)
+    if result.returncode != 0:
+        print("Error getting version: "+str(result.stderr, "utf-8"), \
+                file=STDERR_UTF8)
+        return ""
+    else:
+        return str(result.stdout, "utf-8")
+
+def check_style_is_correct(src_file_list: List[str]) -> bool:
+    """
+    Check the code style and output a diff foir each file whose style is
+    incorrect.
+    """
+    style_correct = True
+    for src_file in src_file_list:
+        uncrustify_cmd = [UNCRUSTIFY_EXE] + UNCRUSTIFY_ARGS + [src_file]
+        subprocess.run(uncrustify_cmd, stdout=subprocess.PIPE, \
+                stderr=subprocess.PIPE, check=False)
+
+        # Uncrustify makes changes to the code and places the result in a new
+        # file with the extension ".uncrustify". To get the changes (if any)
+        # simply diff the 2 files.
+        diff_cmd = ["diff", "-u", src_file, src_file+".uncrustify"]
+        result = subprocess.run(diff_cmd, stdout=subprocess.PIPE, \
+                stderr=STDERR_UTF8, check=False)
+        if len(result.stdout) > 0:
+            print(src_file+" - Incorrect code style.", file=STDOUT_UTF8)
+            print("File changed - diff:", file=STDOUT_UTF8)
+            print(str(result.stdout, "utf-8"), file=STDOUT_UTF8)
+            style_correct = False
+        else:
+            print(src_file+" - OK.", file=STDOUT_UTF8)
+
+        # Tidy up artifact
+        os.remove(src_file+".uncrustify")
+
+    return style_correct
+
+def fix_style_single_pass(src_file_list: List[str]) -> None:
+    """
+    Run Uncrustify once over the source files.
+    """
+    code_change_args = UNCRUSTIFY_ARGS + ["--no-backup"]
+    for src_file in src_file_list:
+        uncrustify_cmd = [UNCRUSTIFY_EXE] + code_change_args + [src_file]
+        subprocess.run(uncrustify_cmd, check=False, stdout=STDOUT_UTF8, \
+                stderr=STDERR_UTF8)
+
+def fix_style(src_file_list: List[str]) -> int:
+    """
+    Fix the code style. This takes 2 passes of Uncrustify.
+    """
+    fix_style_single_pass(src_file_list)
+    fix_style_single_pass(src_file_list)
+
+    # Guard against future changes that cause the codebase to require
+    # more passes.
+    if not check_style_is_correct(src_file_list):
+        print("Error: Code style still incorrect after second run of Uncrustify.", \
+                file=STDERR_UTF8)
+        return 1
+    else:
+        return 0
+
+def main() -> int:
+    """
+    Main with command line arguments.
+    """
+    uncrustify_version = get_uncrustify_version()
+    if "0.75.1" not in uncrustify_version:
+        print("Warning: Using unsupported Uncrustify version '" \
+                + uncrustify_version + "'", file=STDOUT_UTF8)
+
+    src_files = get_src_files()
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-f', '--fix', action='store_true', \
+            help='modify source files to fix the code style')
+
+    args = parser.parse_args()
+
+    if args.fix:
+        # Fix mode
+        return fix_style(src_files)
+    else:
+        # Check mode
+        if check_style_is_correct(src_files):
+            return 0
+        else:
+            return 1
+
+if __name__ == '__main__':
+    sys.exit(main())