diff --git a/ChangeLog b/ChangeLog
index 85d667d060..c9bc8f6478 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,10 +1,13 @@
-Fri Dec 21 13:40:11 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Fri Dec 21 13:46:58 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* encoding.c (rb_enc_register): set encoding constant.
 
 	* encoding.c (rb_enc_find_index): replace non-alphanumeric chars with
 	  underscores, so that initialize function can be called.
 
+	* encoding.c (rb_enc_find_index): extension libraries have lower case
+	  names conventionally.
+
 	* ruby.c (proc_options, process_options): finds encoding after
 	  load_path is initialized.
 
diff --git a/encoding.c b/encoding.c
index fdcceab5a2..ba83837f49 100644
--- a/encoding.c
+++ b/encoding.c
@@ -302,6 +302,7 @@ rb_enc_find_index(const char *name)
 	char *s = RSTRING_PTR(enclib) + 4, *e = RSTRING_END(enclib);
 	while (s < e) {
 	    if (!ISALNUM(*s)) *s = '_';
+	    else if (ISUPPER(*s)) *s = tolower(*s);
 	    ++s;
 	}
 	OBJ_FREEZE(enclib);