diff --git a/ChangeLog b/ChangeLog
index 035b17b75d..84da82d94b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Sep 29 23:17:32 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* io.c (rb_scan_open_args): rb_utf8mac_encoding is undefined.
+
 Tue Sep 29 22:25:41 2009  Tanaka Akira  <akr@fsij.org>
 
 	* include/ruby/intern.h (rb_struct_iv_get): deprecated because it is
diff --git a/io.c b/io.c
index 586e7b5bd6..8bc450d157 100644
--- a/io.c
+++ b/io.c
@@ -5319,7 +5319,7 @@ rb_scan_open_args(int argc, VALUE *argv,
 	if (rb_usascii_encoding() != fname_encoding
 	    && rb_ascii8bit_encoding() != fname_encoding
 	    && rb_utf8_encoding() != fname_encoding
-	    && rb_utf8mac_encoding() != fname_encoding
+	    && utf8mac_encoding != fname_encoding
 	    && fs_encoding != fname_encoding) {
 	    static VALUE fs_enc;
 	    if (!fs_enc)