diff --git a/ChangeLog b/ChangeLog
index 4a8a9f79c2..66eefad252 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Fri Dec 21 14:01:14 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* test/ruby/test_system.rb (TestSystem::valid_syntax): apply
+	  ASCII-8BIT encoding explicitly.
+
+	* re.c (rb_reg_prepare_re): add encoding name in the message.
+
 Fri Dec 21 13:54:05 2007  Tanaka Akira  <akr@fsij.org>
 
 	* re.c: change "character encodings differ" error messages.
diff --git a/re.c b/re.c
index b6facf98ea..9306ae7bfd 100644
--- a/re.c
+++ b/re.c
@@ -943,7 +943,7 @@ rb_reg_prepare_re(VALUE re, VALUE str)
     if (rb_reg_fixed_encoding_p(re)) {
         if (ENCODING_GET(re) != rb_enc_get_index(str) &&
             rb_enc_str_coderange(str) != ENC_CODERANGE_7BIT) {
-            rb_raise(rb_eArgError, "fixed character encoding regexp with incompatible string");
+            rb_raise(rb_eArgError, "fixed character encoding regexp with incompatible string (encoding: %s)", rb_enc_name(rb_enc_get(str)));
         }
     }
     else if ((enc = rb_enc_get(str)) != 0 &&
diff --git a/test/ruby/test_system.rb b/test/ruby/test_system.rb
index 7524b2e7af..403bacab2d 100644
--- a/test/ruby/test_system.rb
+++ b/test/ruby/test_system.rb
@@ -4,6 +4,7 @@ require 'tmpdir'
 
 class TestSystem < Test::Unit::TestCase
   def valid_syntax?(code, fname)
+    code.force_encoding("ascii-8bit")
     code = code.sub(/\A(?:\s*\#.*$)*(\n)?/n) {
       "#$&#{"\n" if $1 && !$2}BEGIN{return true}\n"
     }