diff --git a/mozilla/modules/libjar/nsJARFactory.cpp b/mozilla/modules/libjar/nsJARFactory.cpp
index d1e33ede7af..5a741a98912 100644
--- a/mozilla/modules/libjar/nsJARFactory.cpp
+++ b/mozilla/modules/libjar/nsJARFactory.cpp
@@ -56,6 +56,7 @@
 #include "nsRecyclingAllocator.h"
 #include "nsXPTZipLoader.h"
 #include "nsJARProtocolHandler.h"
+#include "nsJARURI.h"
 
 extern nsRecyclingAllocator *gZlibAllocator;
 
@@ -63,6 +64,7 @@ NS_GENERIC_FACTORY_CONSTRUCTOR(nsXPTZipLoader)
 NS_GENERIC_FACTORY_CONSTRUCTOR(nsJAR)
 NS_GENERIC_FACTORY_CONSTRUCTOR(nsZipReaderCache)
 NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsJARProtocolHandler, Init)
+NS_GENERIC_FACTORY_CONSTRUCTOR(nsJARURI)
 
 // The list of components we register
 static const nsModuleComponentInfo components[] = 
@@ -86,6 +88,11 @@ static const nsModuleComponentInfo components[] =
       NS_JARPROTOCOLHANDLER_CID,
       NS_NETWORK_PROTOCOL_CONTRACTID_PREFIX "jar", 
       nsJARProtocolHandlerConstructor
+    },
+    { NS_JARURI_CLASSNAME, // needed only for fastload
+      NS_JARURI_CID,
+      nsnull,
+      nsJARURIConstructor
     }
 };
 
diff --git a/mozilla/modules/libjar/nsJARURI.cpp b/mozilla/modules/libjar/nsJARURI.cpp
index 646361c5653..6fe8b207004 100644
--- a/mozilla/modules/libjar/nsJARURI.cpp
+++ b/mozilla/modules/libjar/nsJARURI.cpp
@@ -46,6 +46,11 @@
 #include "nsIZipReader.h"
 #include "nsReadableUtils.h"
 #include "nsAutoPtr.h"
+#include "nsNetCID.h"
+#include "nsIObjectInputStream.h"
+#include "nsIObjectOutputStream.h"
+
+static NS_DEFINE_CID(kJARURICID, NS_JARURI_CID);
 
 static NS_DEFINE_CID(kThisImplCID, NS_THIS_JARURI_IMPL_CID);
 
@@ -59,6 +64,7 @@ nsJARURI::~nsJARURI()
 {
 }
 
+// XXX Why is this threadsafe?
 NS_IMPL_THREADSAFE_ADDREF(nsJARURI)
 NS_IMPL_THREADSAFE_RELEASE(nsJARURI)
 NS_INTERFACE_MAP_BEGIN(nsJARURI)
@@ -67,6 +73,7 @@ NS_INTERFACE_MAP_BEGIN(nsJARURI)
   NS_INTERFACE_MAP_ENTRY(nsIURL)
   NS_INTERFACE_MAP_ENTRY(nsIJARURI)
   NS_INTERFACE_MAP_ENTRY(nsISerializable)
+  NS_INTERFACE_MAP_ENTRY(nsIClassInfo)
   // see nsJARURI::Equals
   if (aIID.Equals(kThisImplCID))
       foundInterface = NS_STATIC_CAST(nsIJARURI *, this);
@@ -135,17 +142,98 @@ nsJARURI::CreateEntryURL(const nsACString& entryFilename,
 // nsISerializable methods:
 
 NS_IMETHODIMP
-nsJARURI::Read(nsIObjectInputStream* aStream)
+nsJARURI::Read(nsIObjectInputStream* aInputStream)
 {
-    NS_NOTREACHED("nsJARURI::Read");
-    return NS_ERROR_NOT_IMPLEMENTED;
+    nsresult rv;
+
+    rv = aInputStream->ReadObject(PR_TRUE, getter_AddRefs(mJARFile));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = aInputStream->ReadObject(PR_TRUE, getter_AddRefs(mJAREntry));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = aInputStream->ReadCString(mCharsetHint);
+    return rv;
 }
 
 NS_IMETHODIMP
-nsJARURI::Write(nsIObjectOutputStream* aStream)
+nsJARURI::Write(nsIObjectOutputStream* aOutputStream)
 {
-    NS_NOTREACHED("nsJARURI::Write");
-    return NS_ERROR_NOT_IMPLEMENTED;
+    nsresult rv;
+    
+    rv = aOutputStream->WriteCompoundObject(mJARFile, NS_GET_IID(nsIURI),
+                                            PR_TRUE);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = aOutputStream->WriteCompoundObject(mJAREntry, NS_GET_IID(nsIURL),
+                                            PR_TRUE);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = aOutputStream->WriteStringZ(mCharsetHint.get());
+    return rv;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsIClassInfo methods:
+
+NS_IMETHODIMP 
+nsJARURI::GetInterfaces(PRUint32 *count, nsIID * **array)
+{
+    *count = 0;
+    *array = nsnull;
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsJARURI::GetHelperForLanguage(PRUint32 language, nsISupports **_retval)
+{
+    *_retval = nsnull;
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsJARURI::GetContractID(char * *aContractID)
+{
+    *aContractID = nsnull;
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsJARURI::GetClassDescription(char * *aClassDescription)
+{
+    *aClassDescription = nsnull;
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsJARURI::GetClassID(nsCID * *aClassID)
+{
+    *aClassID = (nsCID*) nsMemory::Alloc(sizeof(nsCID));
+    if (!*aClassID)
+        return NS_ERROR_OUT_OF_MEMORY;
+    return GetClassIDNoAlloc(*aClassID);
+}
+
+NS_IMETHODIMP 
+nsJARURI::GetImplementationLanguage(PRUint32 *aImplementationLanguage)
+{
+    *aImplementationLanguage = nsIProgrammingLanguage::CPLUSPLUS;
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsJARURI::GetFlags(PRUint32 *aFlags)
+{
+    // XXX We implement THREADSAFE addref/release, but probably shouldn't.
+    *aFlags = nsIClassInfo::MAIN_THREAD_ONLY;
+    return NS_OK;
+}
+
+NS_IMETHODIMP 
+nsJARURI::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
+{
+    *aClassIDNoAlloc = kJARURICID;
+    return NS_OK;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/mozilla/modules/libjar/nsJARURI.h b/mozilla/modules/libjar/nsJARURI.h
index ee35a3e5f3d..e16698b199f 100644
--- a/mozilla/modules/libjar/nsJARURI.h
+++ b/mozilla/modules/libjar/nsJARURI.h
@@ -41,6 +41,7 @@
 
 #include "nsIJARURI.h"
 #include "nsISerializable.h"
+#include "nsIClassInfo.h"
 #include "nsCOMPtr.h"
 #include "nsString.h"
 
@@ -52,7 +53,18 @@
     {0xb7, 0x5b, 0xfa, 0x7d, 0x95, 0x70, 0xa6, 0x91} \
 }
 
-class nsJARURI : public nsIJARURI, nsISerializable
+#define NS_JARURI_CLASSNAME \
+    "nsJARURI"
+#define NS_JARURI_CID                                \
+{ /* 245abae2-b947-4ded-a46d-9829d3cca462 */         \
+    0x245abae2,                                      \
+    0xb947,                                          \
+    0x4ded,                                          \
+    {0xa4, 0x6d, 0x98, 0x29, 0xd3, 0xcc, 0xa4, 0x62} \
+}
+
+
+class nsJARURI : public nsIJARURI, nsISerializable, nsIClassInfo
 {
 public:    
     NS_DECL_ISUPPORTS
@@ -60,6 +72,7 @@ public:
     NS_DECL_NSIURL
     NS_DECL_NSIJARURI
     NS_DECL_NSISERIALIZABLE
+    NS_DECL_NSICLASSINFO
 
     // nsJARURI
     nsJARURI();