diff --git a/ChangeLog b/ChangeLog
index c9e5bd1e..5671be13 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2009-02-11  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
+
+	Fixed the bug that adding 0 length filter to BitfieldMan filters 1
+	block. It should not filter anything.
+	* src/BitfieldMan.cc
+	* src/ConsoleStatCalc.cc
+	* test/BitfieldManTest.cc
+
 2009-02-11  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
 
 	Fixed the bug that the boolean options that don't take arguments
diff --git a/src/BitfieldMan.cc b/src/BitfieldMan.cc
index 7940bf25..7421b016 100644
--- a/src/BitfieldMan.cc
+++ b/src/BitfieldMan.cc
@@ -33,10 +33,12 @@
  */
 /* copyright --> */
 #include "BitfieldMan.h"
+
+#include <cstring>
+
 #include "Randomizer.h"
 #include "Util.h"
 #include "array_fun.h"
-#include <cstring>
 
 namespace aria2 {
 
@@ -609,10 +611,12 @@ void BitfieldMan::addFilter(uint64_t offset, uint64_t length) {
     filterBitfield = new unsigned char[bitfieldLength];
     memset(filterBitfield, 0, bitfieldLength);
   }
-  size_t startBlock = offset/blockLength;
-  size_t endBlock = (offset+length-1)/blockLength;
-  for(size_t i = startBlock; i <= endBlock && i < blocks; i++) {
-    setFilterBit(i);
+  if(length > 0) {
+    size_t startBlock = offset/blockLength;
+    size_t endBlock = (offset+length-1)/blockLength;
+    for(size_t i = startBlock; i <= endBlock && i < blocks; i++) {
+      setFilterBit(i);
+    }
   }
   updateCache();
 }
diff --git a/src/ConsoleStatCalc.cc b/src/ConsoleStatCalc.cc
index 89ba1d4e..cbd43984 100644
--- a/src/ConsoleStatCalc.cc
+++ b/src/ConsoleStatCalc.cc
@@ -75,10 +75,14 @@ static void printProgress(std::ostream& o, const SharedHandle<RequestGroup>& rg)
 #ifdef ENABLE_BITTORRENT
   if(rg->downloadFinished() &&
      !dynamic_pointer_cast<BtContext>(rg->getDownloadContext()).isNull()) {
-    o << "SEEDING" << "(" << "ratio:"
-      << std::fixed << std::setprecision(1)
-      << ((stat.getAllTimeUploadLength()*10)/rg->getCompletedLength())/10.0
-      << ")";
+    o << "SEEDING" << "(" << "ratio:";
+    if(rg->getCompletedLength() > 0) {
+      o << std::fixed << std::setprecision(1)
+	<< ((stat.getAllTimeUploadLength()*10)/rg->getCompletedLength())/10.0;
+    } else {
+      o << "--";
+    }
+    o << ")";
   } else
 #endif // ENABLE_BITTORRENT
     {
diff --git a/test/BitfieldManTest.cc b/test/BitfieldManTest.cc
index c1539f9d..d7d6bf9c 100644
--- a/test/BitfieldManTest.cc
+++ b/test/BitfieldManTest.cc
@@ -1,8 +1,11 @@
 #include "BitfieldMan.h"
-#include "FixedNumberRandomizer.h"
+
 #include <cstring>
+
 #include <cppunit/extensions/HelperMacros.h>
 
+#include "FixedNumberRandomizer.h"
+
 namespace aria2 {
 
 class BitfieldManTest:public CppUnit::TestFixture {
@@ -13,6 +16,7 @@ class BitfieldManTest:public CppUnit::TestFixture {
   CPPUNIT_TEST(testGetFirstMissingIndex);
   CPPUNIT_TEST(testIsAllBitSet);
   CPPUNIT_TEST(testFilter);
+  CPPUNIT_TEST(testAddFilter_zeroLength);
   CPPUNIT_TEST(testGetMissingIndex);
   CPPUNIT_TEST(testGetSparceMissingUnusedIndex);
   CPPUNIT_TEST(testGetSparceMissingUnusedIndex_setBit);
@@ -54,6 +58,7 @@ public:
   
   void testIsAllBitSet();
   void testFilter();
+  void testAddFilter_zeroLength();
   void testGetSparceMissingUnusedIndex();
   void testGetSparceMissingUnusedIndex_setBit();
   void testIsBitSetOffsetRange();
@@ -369,6 +374,15 @@ void BitfieldManTest::testFilter() {
 
 }
 
+void BitfieldManTest::testAddFilter_zeroLength()
+{
+  BitfieldMan bits(1024, 1024*1024);
+  bits.addFilter(2048, 0);
+  bits.enableFilter();
+  CPPUNIT_ASSERT_EQUAL((size_t)0, bits.countMissingBlock());
+  CPPUNIT_ASSERT(bits.isFilteredAllBitSet());
+}
+
 void BitfieldManTest::testGetMissingIndex() {
   BitfieldMan bt1(1024, 1024*256);
   bt1.setRandomizer(fixedNumberRandomizer);