diff --git a/lib/test/unit.rb b/lib/test/unit.rb
index 5d279758b0..b72eaa4e9a 100644
--- a/lib/test/unit.rb
+++ b/lib/test/unit.rb
@@ -382,7 +382,7 @@ module Test
       end
 
       def terminal_width
-        unless @terminal_width
+        unless @terminal_width ||= nil
           begin
             require 'io/console'
             width = $stdout.winsize[1]