diff --git a/src/icmtoolchain/output_directory.py b/src/icmtoolchain/output_directory.py
index c833d1e..782bbc3 100644
--- a/src/icmtoolchain/output_directory.py
+++ b/src/icmtoolchain/output_directory.py
@@ -1,7 +1,11 @@
-from os import listdir
-from os.path import basename, exists, isdir, join
+import platform
+from functools import lru_cache
+from os import environ, listdir
+from os.path import basename, exists, expanduser, isdir, join, normpath
 from typing import Callable, List, Optional
 
+from .utils import ensure_not_whitespace
+
 try:
 	from hashlib import blake2s as encode
 except ImportError:
@@ -23,3 +27,47 @@ def expand_paths(file_or_directory: str, filter: Optional[Callable[[str], bool]]
 		if exists(file_or_directory) and (not filter or filter(file_or_directory)):
 			locations.append(file_or_directory)
 	return locations
+
+def get_windows_appdata(csidl: int = 26, env_variable: str = "APPDATA", shell_name: str = "AppData") -> str:
+	try:
+		import ctypes
+	except ImportError:
+		pass
+	else:
+		if hasattr(ctypes, "windll"):
+			buffer = ctypes.create_unicode_buffer(1024)
+			windll = getattr(ctypes, "windll")
+			windll.shell32.SHGetFolderPathW(None, csidl, None, 0, buffer)
+
+			# Downgrade to short path name if it has high-bit chars.
+			if any(ord(c) > 255 for c in buffer):
+				shortest_buffer = ctypes.create_unicode_buffer(1024)
+				if windll.kernel32.GetShortPathNameW(buffer.value, shortest_buffer, 1024):
+					buffer = shortest_buffer
+
+			return buffer.value
+
+	try:
+		import winreg
+	except ImportError:
+		result = environ.get(env_variable)
+		if result is None:
+			raise ValueError(f"Unset environment variable: {env_variable}")
+		return result
+	else:
+		key = winreg.OpenKey(winreg.HKEY_CURRENT_USER, r"Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders")
+		directory, _ = winreg.QueryValueEx(key, shell_name)
+		return str(directory)
+
+@lru_cache
+def get_local_share_directory() -> str:
+	if platform.system() == "Windows":
+		return normpath(get_windows_appdata())
+	path = environ.get("XDG_DATA_HOME", "")
+	if ensure_not_whitespace(path):
+		return path
+	if platform.system() == "Darwin":
+		path = expanduser("~/Library/Application Support")
+	else:
+		path = expanduser("~/.local/share")
+	return path