diff --git a/enum.c b/enum.c
index f49b684f1c..8c8adcfe42 100644
--- a/enum.c
+++ b/enum.c
@@ -3203,7 +3203,7 @@ chunk_i(RB_BLOCK_CALL_FUNC_ARGLIST(yielder, enumerator))
  *  The following example counts words for each initial letter.
  *
  *    open("/usr/share/dict/words", "r:iso-8859-1") { |f|
- *      f.chunk { |line| line.ord }.each { |ch, lines| p [ch.chr, lines.length] }
+ *      f.chunk { |line| line.upcase.ord }.each { |ch, lines| p [ch.chr, lines.length] }
  *    }
  *    #=> ["\n", 1]
  *    #   ["A", 1327]