diff --git a/ChangeLog b/ChangeLog
index 2c89b1e624..5f082e5bdb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+Mon Dec 10 06:44:47 2007  Tanaka Akira  <akr@fsij.org>
+
+	* re.c (rb_reg_expr_str): use \xHH instead of \OOO.
+
+	* regerror.c (to_ascii): ditto.
+	  (onig_snprintf_with_pattern): ditto.
+	  (onig_snprintf_with_pattern): ditto.
+
+	* string.c (rb_str_inspect): ditto.
+	  (rb_str_dump): ditto.
+
+	* parse.y (parser_yylex): ditto.
+
+	* ruby.c (proc_options): ditto.
+
+	* file.c (rb_f_test): ditto.
+
 Mon Dec 10 06:41:00 2007  Tanaka Akira  <akr@fsij.org>
 
 	* re.c (rb_reg_names): new method Regexp#names.
diff --git a/file.c b/file.c
index c3cf72cb33..514bd1de35 100644
--- a/file.c
+++ b/file.c
@@ -3486,7 +3486,7 @@ rb_f_test(int argc, VALUE *argv)
 	rb_raise(rb_eArgError, "unknown command ?%c", cmd);
     }
     else {
-	rb_raise(rb_eArgError, "unknown command ?\\%03o", cmd);
+	rb_raise(rb_eArgError, "unknown command ?\\x%02x", cmd);
     }
     return Qnil;		/* not reached */
 }
diff --git a/parse.y b/parse.y
index 2aff7adaa9..ddfca76626 100644
--- a/parse.y
+++ b/parse.y
@@ -7070,7 +7070,7 @@ parser_yylex(struct parser_params *parser)
 
       default:
 	if (!parser_is_identchar()) {
-	    rb_compile_error(PARSER_ARG  "Invalid char `\\%03o' in expression", c);
+	    rb_compile_error(PARSER_ARG  "Invalid char `\\x%02x' in expression", c);
 	    goto retry;
 	}
 
diff --git a/re.c b/re.c
index 9592e91591..563acbf3af 100644
--- a/re.c
+++ b/re.c
@@ -259,7 +259,7 @@ rb_reg_expr_str(VALUE str, const char *s, long len)
 	    else if (!rb_enc_isspace(c, enc)) {
 		char b[8];
 
-		sprintf(b, "\\%03o", c);
+		sprintf(b, "\\x%02x", c);
 		rb_str_buf_cat(str, b, 4);
 	    }
 	    else {
diff --git a/regerror.c b/regerror.c
index 61187d4a61..cede3f8da6 100644
--- a/regerror.c
+++ b/regerror.c
@@ -197,7 +197,7 @@ static int to_ascii(OnigEncoding enc, UChar *s, UChar *end,
       code = ONIGENC_MBC_TO_CODE(enc, p, end);
       if (code >= 0x80) {
 	if (len + 5 <= buf_size) {
-	  sprintf((char* )(&(buf[len])), "\\%03o",
+	  sprintf((char* )(&(buf[len])), "\\x%02x",
 		  (unsigned int )(code & 0377));
 	  len += 5;
 	}
@@ -346,7 +346,7 @@ onig_snprintf_with_pattern(buf, bufsize, enc, pat, pat_end, fmt, va_alist)
           int blen;
 
           while (len-- > 0) {
-            sprintf((char* )bs, "\\%03o", *p++ & 0377);
+            sprintf((char* )bs, "\\x%02x", *p++ & 0377);
             blen = onigenc_str_bytelen_null(ONIG_ENCODING_ASCII, bs);
             bp = bs;
             while (blen-- > 0) *s++ = *bp++;
@@ -355,7 +355,7 @@ onig_snprintf_with_pattern(buf, bufsize, enc, pat, pat_end, fmt, va_alist)
       }
       else if (!ONIGENC_IS_CODE_PRINT(enc, *p) &&
 	       !ONIGENC_IS_CODE_SPACE(enc, *p)) {
-	sprintf((char* )bs, "\\%03o", *p++ & 0377);
+	sprintf((char* )bs, "\\x%02x", *p++ & 0377);
 	len = onigenc_str_bytelen_null(ONIG_ENCODING_ASCII, bs);
         bp = bs;
 	while (len-- > 0) *s++ = *bp++;
diff --git a/ruby.c b/ruby.c
index 486780467b..fa21bb53b1 100644
--- a/ruby.c
+++ b/ruby.c
@@ -863,7 +863,7 @@ proc_options(int argc, char **argv, struct cmdline_options *opt)
 		}
 		else {
                     rb_raise(rb_eRuntimeError,
-			"invalid option -\\%03o  (-h will show valid options)",
+			"invalid option -\\x%02x  (-h will show valid options)",
                         (int)(unsigned char)*s);
 		}
 	    }
diff --git a/string.c b/string.c
index b716c16b15..a6f8bf1160 100644
--- a/string.c
+++ b/string.c
@@ -2971,7 +2971,7 @@ rb_str_inspect(VALUE str)
 escape_codepoint:
             for (q = p-n; q < p; q++) {
                 s = buf;
-                sprintf(buf, "\\%03o", *q & 0377);
+                sprintf(buf, "\\x%02x", *q & 0377);
                 while (*s) {
                     str_cat_char(result, *s++, enc);
                 }
@@ -3083,7 +3083,7 @@ rb_str_dump(VALUE str)
 	}
 	else {
 	    *q++ = '\\';
-	    sprintf(q, "%03o", c&0xff);
+	    sprintf(q, "x%02x", c&0xff);
 	    q += 3;
 	}
     }
diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index 52b62f6421..5cb6c810da 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -37,7 +37,7 @@ class TestRegexp < Test::Unit::TestCase
   end
 
   def test_to_s
-    assert_equal '(?-mix:\000)', Regexp.new("\0").to_s
+    assert_equal '(?-mix:\x00)', Regexp.new("\0").to_s
   end
 
   def test_union
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index ff9b6f8e70..5657197834 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -444,7 +444,7 @@ class TestString < Test::Unit::TestCase
 
   def test_dump
     a= S("Test") << 1 << 2 << 3 << 9 << 13 << 10
-    assert_equal(S('"Test\\001\\002\\003\\t\\r\\n"'), a.dump)
+    assert_equal(S('"Test\\x01\\x02\\x03\\t\\r\\n"'), a.dump)
   end
 
   def test_dup