diff --git a/ChangeLog b/ChangeLog
index f4468db848..5a9e0077e9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Mar 16 17:18:44 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* include/ruby/encoding.h (rb_str_conv_enc_opts): missing prototype.
+
 Tue Mar 16 15:20:13 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ext/tmpdir: split from lib/tmpdir.rb.
diff --git a/include/ruby/encoding.h b/include/ruby/encoding.h
index 2cac1bcb53..e614ea4a01 100644
--- a/include/ruby/encoding.h
+++ b/include/ruby/encoding.h
@@ -95,6 +95,7 @@ VALUE rb_enc_str_buf_cat(VALUE str, const char *ptr, long len, rb_encoding *enc)
 VALUE rb_external_str_new_with_enc(const char *ptr, long len, rb_encoding *);
 VALUE rb_str_export_to_enc(VALUE, rb_encoding *);
 VALUE rb_str_conv_enc(VALUE str, rb_encoding *from, rb_encoding *to);
+VALUE rb_str_conv_enc_opts(VALUE str, rb_encoding *from, rb_encoding *to, int ecflags, VALUE ecopts);
 
 /* index -> rb_encoding */
 rb_encoding* rb_enc_from_index(int idx);