diff --git a/encoding.c b/encoding.c
index 985dd5bf24..52f311f1ca 100644
--- a/encoding.c
+++ b/encoding.c
@@ -314,7 +314,7 @@ rb_enc_init(void)
 #undef ENC_REGISTER
     enc_alias("ASCII", rb_enc_name(ONIG_ENCODING_ASCII));
     enc_alias("BINARY", rb_enc_name(ONIG_ENCODING_ASCII));
-    enc_alias("eucJP", rb_enc_name(ONIG_ENCODING_EUC_JP));
+    enc_alias("eucJP", rb_enc_name(ONIG_ENCODING_EUC_JP)); /* UI-OSF Application Platform Profile for Japanese Environment Version 1.1 */
     enc_alias("SJIS", rb_enc_name(ONIG_ENCODING_SJIS));
 }