diff --git a/AardClock2.0_Beta.xml b/AardClock2.0_Beta.xml
index da81b2e..384984a 100644
--- a/AardClock2.0_Beta.xml
+++ b/AardClock2.0_Beta.xml
@@ -280,7 +280,7 @@ require 'mw_theme_base'
     end
 
     function center(t)
-        local twid = WindowTextWidth(win, font, t)
+        local twid = WindowTextWidth(win, font, t or 0)
         local cdiff = window_width - twid
 
         return cdiff/2