diff --git a/docshell/base/nsDownloadHistory.cpp b/docshell/base/nsDownloadHistory.cpp
index a6b26b431fa..d62788985a9 100644
--- a/docshell/base/nsDownloadHistory.cpp
+++ b/docshell/base/nsDownloadHistory.cpp
@@ -44,12 +44,43 @@
 #include "nsIGlobalHistory2.h"
 #include "nsIObserverService.h"
 #include "nsIURI.h"
+#include "nsIComponentRegistrar.h"
+#include "nsDocShellCID.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 //// nsDownloadHistory
 
 NS_IMPL_ISUPPORTS1(nsDownloadHistory, nsIDownloadHistory)
 
+nsresult
+nsDownloadHistory::RegisterSelf(nsIComponentManager *aCompMgr,
+                                nsIFile *aPath,
+                                const char *aLoaderStr,
+                                const char *aType,
+                                const nsModuleComponentInfo *aInfo)
+{
+  nsCOMPtr<nsIComponentRegistrar> compReg(do_QueryInterface(aCompMgr));
+  if (!compReg)
+    return NS_ERROR_UNEXPECTED;
+  
+  PRBool registered;
+  nsresult rv = compReg->IsContractIDRegistered(NS_DOWNLOADHISTORY_CONTRACTID,
+                                                &registered);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // If someone has already registered the contractID, we don't want to register
+  // it ourself.  We do want to register though in case someone wants to access
+  // this implementation (by CID).
+  if (registered) {
+    return compReg->RegisterFactoryLocation(GetCID(), "nsDownloadHistory",
+                                            nsnull, aPath, aLoaderStr, aType);
+  }
+
+  return compReg->RegisterFactoryLocation(GetCID(), "nsDownloadHistory",
+                                          NS_DOWNLOADHISTORY_CONTRACTID,
+                                          aPath, aLoaderStr, aType);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 //// nsIDownloadHistory
 
diff --git a/docshell/base/nsDownloadHistory.h b/docshell/base/nsDownloadHistory.h
index 05d28bbf9e8..86bc0778450 100644
--- a/docshell/base/nsDownloadHistory.h
+++ b/docshell/base/nsDownloadHistory.h
@@ -41,6 +41,7 @@
 #define __nsDownloadHistory_h__
 
 #include "nsIDownloadHistory.h"
+#include "nsIGenericFactory.h"
 
 #define NS_DOWNLOADHISTORY_CID \
   {0x2ee83680, 0x2af0, 0x4bcb, {0xbf, 0xa0, 0xc9, 0x70, 0x5f, 0x65, 0x54, 0xf1}}
@@ -50,6 +51,14 @@ class nsDownloadHistory : public nsIDownloadHistory
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIDOWNLOADHISTORY
+
+  static NS_METHOD RegisterSelf(nsIComponentManager *aCompMgr,
+                                nsIFile *aPath,
+                                const char *aLoaderStr,
+                                const char *aType,
+                                const nsModuleComponentInfo *aInfo);
+
+  NS_DEFINE_STATIC_CID_ACCESSOR(NS_DOWNLOADHISTORY_CID)
 };
 
 #endif // __nsDownloadHistory_h__
diff --git a/docshell/build/nsDocShellModule.cpp b/docshell/build/nsDocShellModule.cpp
index d38b31642cb..6138db08eda 100644
--- a/docshell/build/nsDocShellModule.cpp
+++ b/docshell/build/nsDocShellModule.cpp
@@ -250,7 +250,8 @@ static const nsModuleComponentInfo gDocShellModuleInfo[] = {
     
     // download history
     { "nsDownloadHistory", NS_DOWNLOADHISTORY_CID,
-      NS_DOWNLOADHISTORY_CONTRACTID, nsDownloadHistoryConstructor }
+      nsnull, nsDownloadHistoryConstructor,
+      nsDownloadHistory::RegisterSelf }
 };
 
 // "docshell provider" to illustrate that this thing really *should*