diff --git a/pythonosc/osc_message_builder.py b/pythonosc/osc_message_builder.py
index c17da45..9e79079 100644
--- a/pythonosc/osc_message_builder.py
+++ b/pythonosc/osc_message_builder.py
@@ -5,7 +5,7 @@
 from pythonosc import osc_message
 from pythonosc.parsing import osc_types
 
-ArgValue = Union[str, bytes, bool, int, float, osc_types.MidiPacket, list]
+ArgValue = Union[str, bytes, bool, int, float, osc_types.MidiPacket, list, None]
 
 
 class BuildError(Exception):