diff --git a/assets/amalgamate.py b/assets/amalgamate.py
index b471d8e7..4ef633c4 100755
--- a/assets/amalgamate.py
+++ b/assets/amalgamate.py
@@ -2,7 +2,6 @@
 
 from pathlib import Path
 from typing import List, Set
-from glob import glob
 from shutil import rmtree
 
 import os
@@ -19,20 +18,16 @@
 FILE_HEADER = ['// DO NOT EDIT. This file is auto-generated by `amalgamate.py`.', '']
 
 
-# Python versions before 3.10 don't have the root_dir argument for glob, so we 
-# crudely emulate it here.
-def glob_in_dir(
-    pattern: str,
+def find_files(
+    pattern: re.Pattern,
     root_dir: Path,
 ):
-    cwd = os.getcwd()
     root_dir = root_dir.resolve()
-    os.chdir(root_dir)
-    try:
-        for path in glob(pattern, recursive=True):
-            yield Path(root_dir) / path
-    finally:
-        os.chdir(cwd)
+    paths = []
+    for root, dirs, files in os.walk(root_dir):
+        paths.extend([Path(root) / name for name in files if pattern.match(name)])
+
+    return sorted(paths)
 
 
 def find_include_path(
@@ -107,7 +102,7 @@ def merge_sources(*, source_dir: Path, covered_headers: Set[Path]):
         '',
     ]
 
-    for source_file in glob_in_dir('**/*.c', source_dir):
+    for source_file in find_files(re.compile('[\w-]+\.c'), source_dir):
         print(f'Processing source file "{source_file}"')
 
         # Print some comments to show where the code is from.