diff --git a/re.c b/re.c
index 36b89deeb6..17612d48f4 100644
--- a/re.c
+++ b/re.c
@@ -2889,9 +2889,9 @@ rb_reg_match_m(int argc, VALUE *argv, VALUE re)
 
 /*
  *  call-seq:
- *     Regexp.new(string, [options [, lang]])        -> regexp
+ *     Regexp.new(string, [options [, kcode]])        -> regexp
  *     Regexp.new(regexp)                            -> regexp
- *     Regexp.compile(string, [options [, lang]])    -> regexp
+ *     Regexp.compile(string, [options [, kcode]])    -> regexp
  *     Regexp.compile(regexp)                        -> regexp
  *
  *  Constructs a new regular expression from +pattern+, which can be either a
@@ -2903,7 +2903,8 @@ rb_reg_match_m(int argc, VALUE *argv, VALUE re)
  *  <em>or</em>-ed together.  Otherwise, if +options+ is not
  *  +nil+ or +false+, the regexp will be case insensitive.
  *
- *  When the +lang+ parameter is `n' or `N' sets the regexp no encoding.
+ *  When the +kcode+ parameter is `n' or `N' sets the regexp no encoding.
+ *  It means that the regexp is for binary strings.
  *
  *    r1 = Regexp.new('^a-z+:\\s+\w+') #=> /^a-z+:\s+\w+/
  *    r2 = Regexp.new('cat', true)     #=> /cat/i