diff --git a/ChangeLog b/ChangeLog
index 37b0e20924..9d773abb31 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Mar 11 09:52:49 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* string.c (rb_str_comparable): empty strings in any encoding are
+	  compatible each other.
+
 Tue Mar 11 00:46:29 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* ruby.c (usage): remove some unimportant lines to fit -h message
diff --git a/string.c b/string.c
index 53c4027923..2d4b30aec2 100644
--- a/string.c
+++ b/string.c
@@ -1847,20 +1847,23 @@ rb_str_hash_m(VALUE str)
 int
 rb_str_comparable(VALUE str1, VALUE str2)
 {
-    int idx1 = ENCODING_GET(str1);
-    int idx2 = ENCODING_GET(str2);
+    int idx1, idx2;
     int rc1, rc2;
 
+    if (RSTRING_LEN(str1) == 0) return Qtrue;
+    if (RSTRING_LEN(str2) == 0) return Qtrue;
+    idx1 = ENCODING_GET(str1);
+    idx2 = ENCODING_GET(str2);
     if (idx1 == idx2) return Qtrue;
     rc1 = rb_enc_str_coderange(str1);
     rc2 = rb_enc_str_coderange(str2);
     if (rc1 == ENC_CODERANGE_7BIT) {
 	if (rc2 == ENC_CODERANGE_7BIT) return Qtrue;
-	if (rb_enc_asciicompat(rb_enc_from_index(idx1)))
+	if (rb_enc_asciicompat(rb_enc_from_index(idx2)))
 	    return Qtrue;
     }
     if (rc2 == ENC_CODERANGE_7BIT) {
-	if (rb_enc_asciicompat(rb_enc_from_index(idx2)))
+	if (rb_enc_asciicompat(rb_enc_from_index(idx1)))
 	    return Qtrue;
     }
     return Qfalse;