diff --git a/chapter_6.rb b/chapter_6.rb
index 2022952..163ebf0 100644
--- a/chapter_6.rb
+++ b/chapter_6.rb
@@ -45,7 +45,7 @@ def initialize(args)
   def spares
     if style == :road
       { chain:        '10-speed',
-        tire_size:    '23',       # milimeters
+        tire_size:    '23',       # millimeters
         tape_color:   tape_color }
     else
       { chain:        '10-speed',