diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 47639be..0e09440 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -6,8 +6,8 @@ on:
       - 'main'
 
 env:
-  BUILDER_VERSION: better_vectorization_and_crc64
-  BUILDER_SOURCE: channels
+  BUILDER_VERSION: v0.9.63
+  BUILDER_SOURCE: releases
   BUILDER_HOST: https://d19elf31gohf1l.cloudfront.net
   PACKAGE_NAME: aws-checksums
   LINUX_BASE_IMAGE: ubuntu-18-x64
@@ -137,8 +137,8 @@ jobs:
       run: |
         python .\aws-checksums\build\deps\aws-c-common\scripts\appverifier_ctest.py --build_directory .\aws-checksums\build\aws-checksums
 
-  osx:
-    runs-on: macos-12 # latest
+  macos:
+    runs-on: macos-14 # latest
     steps:
     - name: Build ${{ env.PACKAGE_NAME }} + consumers
       run: |
@@ -147,7 +147,7 @@ jobs:
         ./builder build -p ${{ env.PACKAGE_NAME }}
 
   osx-m1:
-    runs-on: macos-latest-xlarge # latest arm build
+    runs-on: macos-14-xlarge # latest arm build
     strategy:
       matrix:
         arch: [ macos-armv8 ]
@@ -158,8 +158,17 @@ jobs:
           chmod a+x builder
           ./builder build -p ${{ env.PACKAGE_NAME }} --target=${{matrix.arch}}
 
-  osx-no-cpu-extensions:
-    runs-on: macos-12 # latest
+  macos-x64:
+    runs-on: macos-14-large # latest
+    steps:
+    - name: Build ${{ env.PACKAGE_NAME }} + consumers
+      run: |
+        python3 -c "from urllib.request import urlretrieve; urlretrieve('${{ env.BUILDER_HOST }}/${{ env.BUILDER_SOURCE }}/${{ env.BUILDER_VERSION }}/builder.pyz?run=${{ env.RUN }}', 'builder')"
+        chmod a+x builder
+        ./builder build -p ${{ env.PACKAGE_NAME }}
+
+  macos-no-cpu-extensions:
+    runs-on: macos-14 # latest
     steps:
     - name: Build ${{ env.PACKAGE_NAME }} + consumers
       run: |
diff --git a/.github/workflows/clang-format.yml b/.github/workflows/clang-format.yml
index cca2eb7..36388d6 100644
--- a/.github/workflows/clang-format.yml
+++ b/.github/workflows/clang-format.yml
@@ -5,14 +5,12 @@ on: [push]
 jobs:
   clang-format:
 
-    runs-on: ubuntu-20.04 # latest
+    runs-on: ubuntu-24.04 # latest
 
     steps:
     - name: Checkout Sources
-      uses: actions/checkout@v1
+      uses: actions/checkout@v4
 
     - name: clang-format lint
-      uses: DoozyX/clang-format-lint-action@v0.3.1
-      with:
-        # List of extensions to check
-        extensions: c,h
+      run: |
+        ./format-check.py
diff --git a/format-check.py b/format-check.py
new file mode 100755
index 0000000..b9e3520
--- /dev/null
+++ b/format-check.py
@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+import argparse
+import os
+from pathlib import Path
+import re
+from subprocess import list2cmdline, run
+from tempfile import NamedTemporaryFile
+
+CLANG_FORMAT_VERSION = '18.1.6'
+
+INCLUDE_REGEX = re.compile(
+    r'^(include|source|tests|verification)/.*\.(c|h|inl)$')
+EXCLUDE_REGEX = re.compile(r'^$')
+
+arg_parser = argparse.ArgumentParser(description="Check with clang-format")
+arg_parser.add_argument('-i', '--inplace-edit', action='store_true',
+                        help="Edit files inplace")
+args = arg_parser.parse_args()
+
+os.chdir(Path(__file__).parent)
+
+# create file containing list of all files to format
+filepaths_file = NamedTemporaryFile(delete=False)
+for dirpath, dirnames, filenames in os.walk('.'):
+    for filename in filenames:
+        # our regexes expect filepath to use forward slash
+        filepath = Path(dirpath, filename).as_posix()
+        if not INCLUDE_REGEX.match(filepath):
+            continue
+        if EXCLUDE_REGEX.match(filepath):
+            continue
+
+        filepaths_file.write(f"{filepath}\n".encode())
+filepaths_file.close()
+
+# use pipx to run clang-format from PyPI
+# this is a simple way to run the same clang-format version regardless of OS
+cmd = ['pipx', 'run', f'clang-format=={CLANG_FORMAT_VERSION}',
+       f'--files={filepaths_file.name}']
+if args.inplace_edit:
+    cmd += ['-i']
+else:
+    cmd += ['--Werror', '--dry-run']
+
+print(f"{Path.cwd()}$ {list2cmdline(cmd)}")
+if run(cmd).returncode:
+    exit(1)
diff --git a/format-check.sh b/format-check.sh
deleted file mode 100755
index 89f1e1a..0000000
--- a/format-check.sh
+++ /dev/null
@@ -1,24 +0,0 @@
-#!/usr/bin/env bash
-
-if [[ -z $CLANG_FORMAT ]] ; then
-    CLANG_FORMAT=clang-format
-fi
-
-if NOT type $CLANG_FORMAT 2> /dev/null ; then
-    echo "No appropriate clang-format found."
-    exit 1
-fi
-
-FAIL=0
-SOURCE_FILES=`find source include tests -type f \( -name '*.h' -o -name '*.c' -o -name '*.inl' \)`
-for i in $SOURCE_FILES
-do
-    $CLANG_FORMAT -output-replacements-xml $i | grep -c "<replacement " > /dev/null
-    if [ $? -ne 1 ]
-    then
-        echo "$i failed clang-format check."
-        FAIL=1
-    fi
-done
-
-exit $FAIL
diff --git a/tests/crc_test.c b/tests/crc_test.c
index 89dda17..53c94a1 100644
--- a/tests/crc_test.c
+++ b/tests/crc_test.c
@@ -13,6 +13,7 @@
 static const uint8_t DATA_32_ZEROS[32] = {0};
 static const uint8_t DATA_32_VALUES[32] = {0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15,
                                            16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31};
+
 static const uint8_t TEST_VECTOR[] = {'1', '2', '3', '4', '5', '6', '7', '8', '9'};
 
 // The polynomial used for CRC32 (in bit-reflected form)