diff --git a/ChangeLog b/ChangeLog
index 23fffa8a04..b300317904 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Dec 13 16:41:37 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* encoding.c (rb_enc_compatible): should not judge compatibility
+	  based on rb_enc_asciicompat().
+
 Thu Dec 13 13:09:03 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* include/ruby/io.h (MakeOpenFile): fptr->enc should be
diff --git a/encoding.c b/encoding.c
index 3f7a39b296..94577a1b24 100644
--- a/encoding.c
+++ b/encoding.c
@@ -388,12 +388,6 @@ rb_enc_compatible(VALUE str1, VALUE str2)
     if (idx1 == idx2) {
 	return rb_enc_from_index(idx1);
     }
-
-    if (idx1 == 0 && rb_enc_asciicompat(enc = rb_enc_from_index(idx2)))
-	return enc;
-    if (idx2 == 0 && rb_enc_asciicompat(enc = rb_enc_from_index(idx1)))
-	return enc;
-
     if (BUILTIN_TYPE(str1) != T_STRING) {
 	VALUE tmp = str1;
 	str1 = str2;