diff --git a/ChangeLog b/ChangeLog
index a0b2841e..dcea068c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2009-06-21  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
+
+	Added comment
+	* src/RequestGroup.cc
+
 2009-06-21  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
 
 	In CookieStorage::load() and saveNsFormat(), handle exception
diff --git a/src/RequestGroup.cc b/src/RequestGroup.cc
index 7def1231..7035e987 100644
--- a/src/RequestGroup.cc
+++ b/src/RequestGroup.cc
@@ -820,6 +820,12 @@ void RequestGroup::releaseRuntimeResource(DownloadEngine* e)
     SharedHandle<BtRegistry> btRegistry = e->getBtRegistry();
     BtContextHandle btContextInReg =
       btRegistry->getBtContext(btContext->getInfoHashAsString());
+    // Make sure that the registered BtContext's GID is equal to
+    // this->getGID().  Even if createInitialCommand() throws
+    // exception without registering this BtContext, after that, this
+    // method is called. In this case, just finding BtContext using
+    // infoHash may detect another download's BtContext and deleting
+    // it from BtRegistry causes Segmentation Fault.
     if(!btContextInReg.isNull() &&
        btContextInReg->getOwnerRequestGroup()->getGID() ==
 	btContext->getOwnerRequestGroup()->getGID()) {