diff --git a/poezio/windows/funcs.py b/poezio/windows/funcs.py
index 69edace2..22977374 100644
--- a/poezio/windows/funcs.py
+++ b/poezio/windows/funcs.py
@@ -22,7 +22,7 @@ def find_first_format_char(text: str,
     return pos
 
 
-def truncate_nick(nick: str, size=10) -> str:
+def truncate_nick(nick: Optional[str], size=10) -> Optional[str]:
     if size < 1:
         size = 1
     if nick and len(nick) > size: