diff --git a/ChangeLog b/ChangeLog
index 10a7922520..96b8fd5093 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Oct 14 09:46:28 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* sprintf.c (rb_str_format): fix: sprintf with hex format and
+	  precision includes wrong dots.
+
 Fri Oct 15 16:40:37 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* pack.c (pack_pack): fix more than one modifiers appear in the
diff --git a/sprintf.c b/sprintf.c
index 21509eafdd..0e97955161 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -844,7 +844,7 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 		    }
 		    else {
 			s = nbuf;
-			if (v < 0) {
+			if (v < 0 && !(flags & FPREC0)) {
 			    dots = 1;
 			}
 			snprintf(fbuf, sizeof(fbuf), "%%l%c", *p == 'X' ? 'x' : *p);
@@ -892,7 +892,8 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 			tmp1 = tmp = rb_big2str0(val, base, RBIGNUM_SIGN(val));
 			s = RSTRING_PTR(tmp);
 			if (*s == '-') {
-			    dots = 1;
+			    if (!(flags & FPREC0))
+				dots = 1;
 			    if (base == 10) {
 				rb_warning("negative number for %%u specifier");
 			    }
@@ -925,14 +926,11 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 		    }
 		}
 		if (prefix && !prefix[1]) { /* octal */
-		    if (dots) {
-			prefix = 0;
-		    }
-		    else if (len == 1 && *s == '0') {
+		    if (len == 1 && *s == '0') {
 			len = 0;
 			if (flags & FPREC) prec--;
 		    }
-		    else if ((flags & FPREC) && (prec > len)) {
+		    else if ((flags & FPREC) && (prec > len) && v >= 0) {
 			prefix = 0;
 		    }
 		}
diff --git a/test/ruby/test_sprintf.rb b/test/ruby/test_sprintf.rb
index 96a1b62bb7..24b6a34b3a 100644
--- a/test/ruby/test_sprintf.rb
+++ b/test/ruby/test_sprintf.rb
@@ -24,12 +24,12 @@ class TestSprintf < Test::Unit::TestCase
     assert_equal("0000", sprintf("%.4b", 0))
     assert_equal("0001", sprintf("%.4b", 1))
     assert_equal("0010", sprintf("%.4b", 2))
-    assert_equal("..11", sprintf("%.4b", -1))
+    assert_equal("1111", sprintf("%.4b", -1))
 
     assert_equal("  0000", sprintf("%6.4b", 0))
     assert_equal("  0001", sprintf("%6.4b", 1))
     assert_equal("  0010", sprintf("%6.4b", 2))
-    assert_equal("  ..11", sprintf("%6.4b", -1))
+    assert_equal("  1111", sprintf("%6.4b", -1))
 
     assert_equal("   0", sprintf("%#4b", 0))
     assert_equal(" 0b1", sprintf("%#4b", 1))
@@ -44,12 +44,12 @@ class TestSprintf < Test::Unit::TestCase
     assert_equal("0000", sprintf("%#.4b", 0))
     assert_equal("0b0001", sprintf("%#.4b", 1))
     assert_equal("0b0010", sprintf("%#.4b", 2))
-    assert_equal("0b..11", sprintf("%#.4b", -1))
+    assert_equal("0b1111", sprintf("%#.4b", -1))
 
     assert_equal("  0000", sprintf("%#6.4b", 0))
     assert_equal("0b0001", sprintf("%#6.4b", 1))
     assert_equal("0b0010", sprintf("%#6.4b", 2))
-    assert_equal("0b..11", sprintf("%#6.4b", -1))
+    assert_equal("0b1111", sprintf("%#6.4b", -1))
 
     assert_equal("+0", sprintf("%+b", 0))
     assert_equal("+1", sprintf("%+b", 1))
@@ -288,6 +288,8 @@ class TestSprintf < Test::Unit::TestCase
     b1 = (/\.\./ =~ s1) != nil
     b2 = (/\.\./ =~ s2) != nil
     assert(b1 == b2, "[ruby-dev:33224]")
+
+    assert_equal("ffffffff", sprintf("%.8x", -1))
   end
 
   def test_named
diff --git a/test/ruby/test_sprintf_comb.rb b/test/ruby/test_sprintf_comb.rb
index 261732bcbc..3105127046 100644
--- a/test/ruby/test_sprintf_comb.rb
+++ b/test/ruby/test_sprintf_comb.rb
@@ -190,7 +190,7 @@ class TestSprintfComb < Test::Unit::TestCase
         if digits.last != radix-1
           digits << (radix-1)
         end
-        sign = '..'
+        sign = '..' unless precision
       else
         sign = '-'
       end
@@ -222,8 +222,8 @@ class TestSprintfComb < Test::Unit::TestCase
       end
     end
     if type == 'o' && hs
-      if digits.empty? || digits.last != d
-        digits << d
+      if digits.empty? || digits.last != 0
+        prefix = '0'
       end
     end