diff --git a/ChangeLog b/ChangeLog
index ccf0ec729b..a53598ef19 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Mar 22 10:29:25 2007  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* test/ruby/test_bignum.rb (test_to_s): add tests for Bignum#to_s.
+
 Wed Mar 21 17:04:30 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* bignum.c (rb_big2str0): round up for the most significant digit.
diff --git a/test/ruby/test_bignum.rb b/test/ruby/test_bignum.rb
index c238337db5..48e8d9a92c 100644
--- a/test/ruby/test_bignum.rb
+++ b/test/ruby/test_bignum.rb
@@ -84,4 +84,15 @@ class TestBignum < Test::Unit::TestCase
     shift_test(-4518325415524767873)
     shift_test(-0xfffffffffffffffff)
   end
+
+  def test_to_s  # [ruby-core:10686]
+    assert_equal("fvvvvvvvvvvvv" ,18446744073709551615.to_s(32))
+    assert_equal("g000000000000" ,18446744073709551616.to_s(32))
+    assert_equal("3w5e11264sgsf" ,18446744073709551615.to_s(36))
+    assert_equal("3w5e11264sgsg" ,18446744073709551616.to_s(36))
+    assert_equal("nd075ib45k86f" ,18446744073709551615.to_s(31))
+    assert_equal("nd075ib45k86g" ,18446744073709551616.to_s(31))
+    assert_equal("1777777777777777777777" ,18446744073709551615.to_s(8))
+    assert_equal("-1777777777777777777777" ,-18446744073709551615.to_s(8))
+  end
 end
diff --git a/version.h b/version.h
index 0b58e18dd2..7b8fa194a1 100644
--- a/version.h
+++ b/version.h
@@ -1,7 +1,7 @@
 #define RUBY_VERSION "1.8.6"
-#define RUBY_RELEASE_DATE "2007-03-21"
+#define RUBY_RELEASE_DATE "2007-03-22"
 #define RUBY_VERSION_CODE 186
-#define RUBY_RELEASE_CODE 20070321
+#define RUBY_RELEASE_CODE 20070322
 #define RUBY_PATCHLEVEL 5000
 
 #define RUBY_VERSION_MAJOR 1
@@ -9,7 +9,7 @@
 #define RUBY_VERSION_TEENY 6
 #define RUBY_RELEASE_YEAR 2007
 #define RUBY_RELEASE_MONTH 3
-#define RUBY_RELEASE_DAY 21
+#define RUBY_RELEASE_DAY 22
 
 RUBY_EXTERN const char ruby_version[];
 RUBY_EXTERN const char ruby_release_date[];