diff --git a/PyTeX/format/formatting_config.py b/PyTeX/format/formatting_config.py
index 2888b0f..49aaaee 100644
--- a/PyTeX/format/formatting_config.py
+++ b/PyTeX/format/formatting_config.py
@@ -1,4 +1,4 @@
-from typing import List, Optional, Dict
+from typing import List, Optional, Dict, Union
 
 from .config import Config, recursive_merge_dictionaries
 from .enums import NamingScheme