diff --git a/transcode.c b/transcode.c
index 3a37c63987..034a4829a9 100644
--- a/transcode.c
+++ b/transcode.c
@@ -2784,14 +2784,14 @@ str_encode_associate(VALUE str, int encidx)

 /*
  *  call-seq:
- *     str.encode!(encoding [, options] )   -> str
- *     str.encode!(dst_encoding, src_encoding [, options] )   -> str
+ *     str.encode!(encoding [, **options] )   -> str
+ *     str.encode!(dst_encoding, src_encoding [, **options] )   -> str
  *
  *  The first form transcodes the contents of <i>str</i> from
  *  str.encoding to +encoding+.
  *  The second form transcodes the contents of <i>str</i> from
  *  src_encoding to dst_encoding.
- *  The options Hash gives details for conversion. See String#encode
+ *  The <tt>**options</tt> keyword arguments give details for conversion. See String#encode
  *  for details.
  *  Returns the string even if no changes were made.
  */
@@ -2820,9 +2820,9 @@ static VALUE encoded_dup(VALUE newstr, VALUE str, int encidx);

 /*
  *  call-seq:
- *     str.encode(encoding [, options] )   -> str
- *     str.encode(dst_encoding, src_encoding [, options] )   -> str
- *     str.encode([options])   -> str
+ *     str.encode(encoding [, **options] )   -> str
+ *     str.encode(dst_encoding, src_encoding [, **options] )   -> str
+ *     str.encode([**options])   -> str
  *
  *  The first form returns a copy of +str+ transcoded
  *  to encoding +encoding+.
@@ -2838,8 +2838,8 @@ static VALUE encoded_dup(VALUE newstr, VALUE str, int encidx);
  *  in the source encoding. The last form by default does not raise
  *  exceptions but uses replacement strings.
  *
- *  The +options+ Hash gives details for conversion and can have the following
- *  keys:
+ *  The <tt>**options</tt> keyword arguments give details for conversion.
+ *  The arguments are:
  *
  *  :invalid ::
  *    If the value is +:replace+, #encode replaces invalid byte sequences in