diff --git a/io.c b/io.c
index dd42423c25..f4698a2cd5 100644
--- a/io.c
+++ b/io.c
@@ -15059,7 +15059,7 @@ set_LAST_READ_LINE(VALUE val, ID _x, VALUE *_y)
  *      # => 41
  *      f.close
  *
- *  - When a stream is read, <tt>#.</tt> is set to the line number for that stream:
+ *  - When a stream is read, <tt>$.</tt> is set to the line number for that stream:
  *
  *      f0 = File.new('t.txt')
  *      f1 = File.new('t.dat')