diff --git a/mozilla/mailnews/base/src/nsMsgFolderCompactor.cpp b/mozilla/mailnews/base/src/nsMsgFolderCompactor.cpp
index eca80b11b39..ded5ee7e8fc 100644
--- a/mozilla/mailnews/base/src/nsMsgFolderCompactor.cpp
+++ b/mozilla/mailnews/base/src/nsMsgFolderCompactor.cpp
@@ -264,6 +264,7 @@ nsFolderCompactState::Init(nsIMsgFolder *folder, const char *baseMsgUri, nsIMsgD
 
   pathSpec->GetFileSpec(&m_fileSpec);
   m_fileSpec.SetLeafName("nstmp");
+  m_fileSpec.MakeUnique();   //make sure we are not crunching existing nstmp file
   m_window = aMsgWindow;
   m_keyArray.RemoveAll();
   InitDB(db);