diff --git a/reg_extension_icon.py b/reg_extension_icon.py
new file mode 100644
index 0000000..85575cf
--- /dev/null
+++ b/reg_extension_icon.py
@@ -0,0 +1,68 @@
+'''
+I create my own icon files for some file types. This script edits the windows
+registry to assign the file extension icon and optionally a human-friendly name
+string. Must run as administrator.
+
+WARNING, if the extension is already associated with a program, or is otherwise
+connected to a progid, this will break it.
+'''
+import argparse
+import sys
+import winreg
+
+from voussoirkit import getpermission
+from voussoirkit import pathclass
+
+def extension_registry(ico_file, human_name=None):
+    if ico_file.extension != 'ico':
+        raise ValueError('Must provide a .ico file.')
+
+    name = ico_file.replace_extension('').basename
+
+    dot_ex = f'.{name}'
+    hash_ex = f'#{name}'
+
+    prompt = [
+        f'Set {dot_ex} = {hash_ex}',
+        f'Set {hash_ex}\\DefaultIcon = {ico_file.absolute_path}',
+    ]
+
+    if human_name:
+        prompt.append(f'Set {hash_ex} = {human_name}')
+
+    prompt = '\n'.join(prompt)
+
+    if not getpermission.getpermission(prompt):
+        return
+
+    dot_key = winreg.CreateKey(winreg.HKEY_CLASSES_ROOT, dot_ex)
+    winreg.SetValueEx(dot_key, '', 0, winreg.REG_SZ, hash_ex)
+
+    hash_key = winreg.CreateKey(winreg.HKEY_CLASSES_ROOT, hash_ex)
+    if human_name:
+        winreg.SetValueEx(hash_key, '', 0, winreg.REG_SZ, human_name)
+
+    icon_key = winreg.CreateKey(winreg.HKEY_CLASSES_ROOT, f'{hash_ex}\\DefaultIcon')
+    winreg.SetValueEx(icon_key, '', 0, winreg.REG_SZ, ico_file.absolute_path)
+
+    print('Finished.')
+
+
+def extension_registry_argparse(args):
+    return extension_registry(
+        ico_file=pathclass.Path(args.ico_file),
+        human_name=args.name,
+    )
+
+def main(argv):
+    parser = argparse.ArgumentParser(description=__doc__)
+
+    parser.add_argument('ico_file')
+    parser.add_argument('--name', dest='name', default=None)
+    parser.set_defaults(func=extension_registry_argparse)
+
+    args = parser.parse_args(argv)
+    return args.func(args)
+
+if __name__ == '__main__':
+    raise SystemExit(main(sys.argv[1:]))