diff --git a/kitty/tab_bar.py b/kitty/tab_bar.py
index 6dd6a6a9c1..8ab27fc5c2 100644
--- a/kitty/tab_bar.py
+++ b/kitty/tab_bar.py
@@ -27,6 +27,7 @@
     set_tab_bar_render_data,
     update_tab_bar_edge_colors,
     viewport_for_window,
+    wcswidth,
 )
 from .rgb import alpha_blend, color_as_sgr, color_from_int, to_color
 from .types import WindowGeometry, run_once
@@ -221,6 +222,7 @@ def active_oldest_exe(self) -> str:
 
 safe_builtins = {
     'max': max, 'min': min, 'str': str, 'repr': repr, 'abs': abs, 'len': len, 'chr': chr, 'ord': ord, 're': re,
+    'wcswidth': wcswidth,
 }